diff --git a/analysis.json b/analysis.json
index 69d26e0..ee360b0 100644
--- a/analysis.json
+++ b/analysis.json
@@ -6,13 +6,13 @@
       "description": "",
       "summary": "",
       "sourceRange": {
-        "file": "src/vaadin-radio-group.html",
+        "file": "src/vaadin-field.html",
         "start": {
-          "line": 294,
+          "line": 266,
           "column": 6
         },
         "end": {
-          "line": 294,
+          "line": 266,
           "column": 42
         }
       },
@@ -816,9 +816,9 @@
           ]
         },
         {
-          "description": "`<vaadin-radio-group>` is a Polymer element for grouping vaadin-radio-buttons.\n\n```html\n<vaadin-radio-group>\n  <vaadin-radio-button name=\"foo\">Foo</vaadin-radio-button>\n  <vaadin-radio-button name=\"bar\">Bar</vaadin-radio-button>\n  <vaadin-radio-button name=\"baz\">Baz</vaadin-radio-button>\n</vaadin-radio-group>\n```\n\n### Styling\n\nThe following shadow DOM parts are available for styling:\n\nPart name | Description\n----------------|----------------\n`label` | The label element\n\nThe following state attributes are available for styling:\n\nAttribute  | Description | Part name\n-----------|-------------|------------\n`disabled` | Set when the radio group and its children are disabled. | :host\n`has-label` | Set when the element has a label | :host\n\nSee [ThemableMixin – how to apply styles for shadow parts](https://github.com/vaadin/vaadin-themable-mixin/wiki)",
+          "description": "`<vaadin-radio-group>` is a Polymer element for grouping vaadin-radio-buttons.\n\n```html\n<vaadin-radio-group>\n  <vaadin-radio-button name=\"foo\">Foo</vaadin-radio-button>\n  <vaadin-radio-button name=\"bar\">Bar</vaadin-radio-button>\n  <vaadin-radio-button name=\"baz\">Baz</vaadin-radio-button>\n</vaadin-radio-group>\n```\n\n### Styling\n\nThe following shadow DOM parts are available for styling:\n\nPart name | Description\n----------------|----------------\n`label` | The label element\n`group-field` | The element that wraps radio-buttons\n\nThe following state attributes are available for styling:\n\nAttribute  | Description | Part name\n-----------|-------------|------------\n`disabled`   | Set when the radio group and its children are disabled. | :host\n`readonly` | Set to a readonly text field | :host\n`invalid` | Set when the element is invalid | :host\n`has-label` | Set when the element has a label | :host\n\nSee [ThemableMixin – how to apply styles for shadow parts](https://github.com/vaadin/vaadin-themable-mixin/wiki)",
           "summary": "",
-          "path": "src/vaadin-field.html",
+          "path": "src/vaadin-radio-group.html",
           "properties": [
             {
               "name": "_radioButtons",
@@ -827,11 +827,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 136,
+                  "line": 214,
                   "column": 8
                 },
                 "end": {
-                  "line": 138,
+                  "line": 216,
                   "column": 9
                 }
               },
@@ -848,11 +848,11 @@
               "privacy": "public",
               "sourceRange": {
                 "start": {
-                  "line": 67,
+                  "line": 101,
                   "column": 12
                 },
                 "end": {
-                  "line": 71,
+                  "line": 105,
                   "column": 13
                 }
               },
@@ -863,6 +863,115 @@
                 }
               }
             },
+            {
+              "name": "readonly",
+              "type": "boolean | null | undefined",
+              "description": "This attribute indicates that the user cannot modify the value of the control.",
+              "privacy": "public",
+              "sourceRange": {
+                "start": {
+                  "line": 110,
+                  "column": 12
+                },
+                "end": {
+                  "line": 114,
+                  "column": 13
+                }
+              },
+              "metadata": {
+                "polymer": {
+                  "observer": "\"_readonlyChanged\"",
+                  "attributeType": "Boolean"
+                }
+              }
+            },
+            {
+              "name": "invalid",
+              "type": "boolean | null | undefined",
+              "description": "This property is set to true when the value is invalid.",
+              "privacy": "public",
+              "sourceRange": {
+                "start": {
+                  "line": 119,
+                  "column": 12
+                },
+                "end": {
+                  "line": 124,
+                  "column": 13
+                }
+              },
+              "metadata": {
+                "polymer": {
+                  "notify": true,
+                  "attributeType": "Boolean"
+                }
+              },
+              "defaultValue": "false"
+            },
+            {
+              "name": "required",
+              "type": "boolean | null | undefined",
+              "description": "Specifies that the user must fill in a value.",
+              "privacy": "public",
+              "sourceRange": {
+                "start": {
+                  "line": 129,
+                  "column": 12
+                },
+                "end": {
+                  "line": 132,
+                  "column": 13
+                }
+              },
+              "metadata": {
+                "polymer": {
+                  "attributeType": "Boolean"
+                }
+              }
+            },
+            {
+              "name": "errorMessage",
+              "type": "string | null | undefined",
+              "description": "Error to show when the input value is invalid.",
+              "privacy": "public",
+              "sourceRange": {
+                "start": {
+                  "line": 137,
+                  "column": 12
+                },
+                "end": {
+                  "line": 140,
+                  "column": 13
+                }
+              },
+              "metadata": {
+                "polymer": {
+                  "attributeType": "String"
+                }
+              },
+              "defaultValue": "\"\""
+            },
+            {
+              "name": "_errorId",
+              "type": "string | null | undefined",
+              "description": "",
+              "privacy": "protected",
+              "sourceRange": {
+                "start": {
+                  "line": 142,
+                  "column": 12
+                },
+                "end": {
+                  "line": 144,
+                  "column": 13
+                }
+              },
+              "metadata": {
+                "polymer": {
+                  "attributeType": "String"
+                }
+              }
+            },
             {
               "name": "_checkedButton",
               "type": "Object | null | undefined",
@@ -870,11 +979,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 73,
+                  "line": 146,
                   "column": 12
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-                  "line": 76,
+                  "line": 149,
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               },
@@ -892,11 +1001,11 @@
               "privacy": "public",
               "sourceRange": {
                 "start": {
-                  "line": 81,
+                  "line": 154,
                   "column": 12
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-                  "line": 85,
+                  "line": 158,
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@@ -915,11 +1024,11 @@
               "privacy": "public",
               "sourceRange": {
                 "start": {
-                  "line": 90,
+                  "line": 163,
                   "column": 12
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                 "end": {
-                  "line": 94,
+                  "line": 167,
                   "column": 13
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@@ -939,11 +1048,11 @@
               "privacy": "private",
               "sourceRange": {
                 "start": {
-                  "line": 101,
+                  "line": 174,
                   "column": 8
                 },
                 "end": {
-                  "line": 122,
+                  "line": 195,
                   "column": 9
                 }
               },
@@ -959,11 +1068,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 124,
+                  "line": 197,
                   "column": 8
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-                  "line": 134,
+                  "line": 212,
                   "column": 9
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@@ -979,11 +1088,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 140,
+                  "line": 218,
                   "column": 8
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-                  "line": 143,
+                  "line": 221,
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               },
@@ -1000,11 +1109,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 145,
+                  "line": 223,
                   "column": 8
                 },
                 "end": {
-                  "line": 149,
+                  "line": 226,
                   "column": 9
                 }
               },
@@ -1018,17 +1127,64 @@
                 "type": "void"
               }
             },
+            {
+              "name": "_updateDisableButtons",
+              "description": "",
+              "privacy": "protected",
+              "sourceRange": {
+                "start": {
+                  "line": 228,
+                  "column": 8
+                },
+                "end": {
+                  "line": 240,
+                  "column": 9
+                }
+              },
+              "metadata": {},
+              "params": [],
+              "return": {
+                "type": "void"
+              }
+            },
+            {
+              "name": "_readonlyChanged",
+              "description": "",
+              "privacy": "protected",
+              "sourceRange": {
+                "start": {
+                  "line": 242,
+                  "column": 8
+                },
+                "end": {
+                  "line": 244,
+                  "column": 9
+                }
+              },
+              "metadata": {},
+              "params": [
+                {
+                  "name": "newV"
+                },
+                {
+                  "name": "oldV"
+                }
+              ],
+              "return": {
+                "type": "void"
+              }
+            },
             {
               "name": "_addActiveListeners",
               "description": "",
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 151,
+                  "line": 246,
                   "column": 8
                 },
                 "end": {
-                  "line": 171,
+                  "line": 263,
                   "column": 9
                 }
               },
@@ -1044,11 +1200,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 173,
+                  "line": 265,
                   "column": 8
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-                  "line": 181,
+                  "line": 273,
                   "column": 9
                 }
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@@ -1071,11 +1227,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 183,
+                  "line": 275,
                   "column": 8
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-                  "line": 188,
+                  "line": 280,
                   "column": 9
                 }
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@@ -1088,11 +1244,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 190,
+                  "line": 283,
                   "column": 8
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                 "end": {
-                  "line": 192,
+                  "line": 285,
                   "column": 9
                 }
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@@ -1105,11 +1261,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 194,
+                  "line": 287,
                   "column": 8
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                 "end": {
-                  "line": 206,
+                  "line": 299,
                   "column": 9
                 }
               },
@@ -1129,11 +1285,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 208,
+                  "line": 301,
                   "column": 8
                 },
                 "end": {
-                  "line": 220,
+                  "line": 313,
                   "column": 9
                 }
               },
@@ -1153,11 +1309,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 222,
+                  "line": 315,
                   "column": 8
                 },
                 "end": {
-                  "line": 226,
+                  "line": 319,
                   "column": 9
                 }
               },
@@ -1177,11 +1333,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 228,
+                  "line": 321,
                   "column": 8
                 },
                 "end": {
-                  "line": 232,
+                  "line": 325,
                   "column": 9
                 }
               },
@@ -1201,11 +1357,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 234,
+                  "line": 327,
                   "column": 8
                 },
                 "end": {
-                  "line": 244,
+                  "line": 343,
                   "column": 9
                 }
               },
@@ -1222,17 +1378,58 @@
                 "type": "void"
               }
             },
+            {
+              "name": "validate",
+              "description": "Returns true if `value` is valid.\n`<iron-form>` uses this to check the validity or all its elements.",
+              "privacy": "public",
+              "sourceRange": {
+                "start": {
+                  "line": 351,
+                  "column": 8
+                },
+                "end": {
+                  "line": 353,
+                  "column": 9
+                }
+              },
+              "metadata": {},
+              "params": [],
+              "return": {
+                "type": "boolean",
+                "desc": "True if the value is valid."
+              }
+            },
+            {
+              "name": "checkValidity",
+              "description": "Returns true if the current input value satisfies all constraints (if any)",
+              "privacy": "public",
+              "sourceRange": {
+                "start": {
+                  "line": 359,
+                  "column": 8
+                },
+                "end": {
+                  "line": 361,
+                  "column": 9
+                }
+              },
+              "metadata": {},
+              "params": [],
+              "return": {
+                "type": "boolean"
+              }
+            },
             {
               "name": "_setFocusable",
               "description": "",
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 246,
+                  "line": 363,
                   "column": 8
                 },
                 "end": {
-                  "line": 249,
+                  "line": 366,
                   "column": 9
                 }
               },
@@ -1252,11 +1449,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 251,
+                  "line": 368,
                   "column": 8
                 },
                 "end": {
-                  "line": 257,
+                  "line": 374,
                   "column": 9
                 }
               },
@@ -1269,6 +1466,60 @@
               "return": {
                 "type": "void"
               }
+            },
+            {
+              "name": "_getActiveErrorId",
+              "description": "",
+              "privacy": "protected",
+              "sourceRange": {
+                "start": {
+                  "line": 376,
+                  "column": 8
+                },
+                "end": {
+                  "line": 378,
+                  "column": 9
+                }
+              },
+              "metadata": {},
+              "params": [
+                {
+                  "name": "invalid"
+                },
+                {
+                  "name": "errorMessage"
+                },
+                {
+                  "name": "errorId"
+                }
+              ]
+            },
+            {
+              "name": "_getErrorMessageAriaHidden",
+              "description": "",
+              "privacy": "protected",
+              "sourceRange": {
+                "start": {
+                  "line": 380,
+                  "column": 8
+                },
+                "end": {
+                  "line": 382,
+                  "column": 9
+                }
+              },
+              "metadata": {},
+              "params": [
+                {
+                  "name": "invalid"
+                },
+                {
+                  "name": "errorMessage"
+                },
+                {
+                  "name": "errorId"
+                }
+              ]
             }
           ],
           "staticMethods": [
@@ -1359,11 +1610,11 @@
           "metadata": {},
           "sourceRange": {
             "start": {
-              "line": 57,
+              "line": 91,
               "column": 6
             },
             "end": {
-              "line": 259,
+              "line": 383,
               "column": 7
             }
           },
@@ -1376,27 +1627,91 @@
               "description": "The current disabled state of the radio group. True if group and all internal radio buttons are disabled.",
               "sourceRange": {
                 "start": {
-                  "line": 67,
+                  "line": 101,
                   "column": 12
                 },
                 "end": {
-                  "line": 71,
+                  "line": 105,
+                  "column": 13
+                }
+              },
+              "metadata": {},
+              "type": "boolean | null | undefined"
+            },
+            {
+              "name": "readonly",
+              "description": "This attribute indicates that the user cannot modify the value of the control.",
+              "sourceRange": {
+                "start": {
+                  "line": 110,
+                  "column": 12
+                },
+                "end": {
+                  "line": 114,
+                  "column": 13
+                }
+              },
+              "metadata": {},
+              "type": "boolean | null | undefined"
+            },
+            {
+              "name": "invalid",
+              "description": "This property is set to true when the value is invalid.",
+              "sourceRange": {
+                "start": {
+                  "line": 119,
+                  "column": 12
+                },
+                "end": {
+                  "line": 124,
+                  "column": 13
+                }
+              },
+              "metadata": {},
+              "type": "boolean | null | undefined"
+            },
+            {
+              "name": "required",
+              "description": "Specifies that the user must fill in a value.",
+              "sourceRange": {
+                "start": {
+                  "line": 129,
+                  "column": 12
+                },
+                "end": {
+                  "line": 132,
                   "column": 13
                 }
               },
               "metadata": {},
               "type": "boolean | null | undefined"
             },
+            {
+              "name": "error-message",
+              "description": "Error to show when the input value is invalid.",
+              "sourceRange": {
+                "start": {
+                  "line": 137,
+                  "column": 12
+                },
+                "end": {
+                  "line": 140,
+                  "column": 13
+                }
+              },
+              "metadata": {},
+              "type": "string | null | undefined"
+            },
             {
               "name": "label",
               "description": "String used for the label element.",
               "sourceRange": {
                 "start": {
-                  "line": 81,
+                  "line": 154,
                   "column": 12
                 },
                 "end": {
-                  "line": 85,
+                  "line": 158,
                   "column": 13
                 }
               },
@@ -1408,11 +1723,11 @@
               "description": "Value of the radio group.",
               "sourceRange": {
                 "start": {
-                  "line": 90,
+                  "line": 163,
                   "column": 12
                 },
                 "end": {
-                  "line": 94,
+                  "line": 167,
                   "column": 13
                 }
               },
@@ -1421,6 +1736,12 @@
             }
           ],
           "events": [
+            {
+              "type": "CustomEvent",
+              "name": "invalid-changed",
+              "description": "Fired when the `invalid` property changes.",
+              "metadata": {}
+            },
             {
               "type": "CustomEvent",
               "name": "value-changed",
@@ -1438,12 +1759,12 @@
               "name": "",
               "range": {
                 "start": {
-                  "line": 19,
-                  "column": 4
+                  "line": 42,
+                  "column": 8
                 },
                 "end": {
-                  "line": 19,
-                  "column": 27
+                  "line": 42,
+                  "column": 31
                 }
               }
             }
@@ -1454,9 +1775,9 @@
           ]
         },
         {
-          "description": "`<vaadin-radio-group>` is a Polymer element for grouping vaadin-radio-buttons.\n\n```html\n<vaadin-radio-group>\n  <vaadin-radio-button name=\"foo\">Foo</vaadin-radio-button>\n  <vaadin-radio-button name=\"bar\">Bar</vaadin-radio-button>\n  <vaadin-radio-button name=\"baz\">Baz</vaadin-radio-button>\n</vaadin-radio-group>\n```\n\n### Styling\n\nThe following shadow DOM parts are available for styling:\n\nPart name | Description\n----------------|----------------\n`label` | The label element\n`group-field` | The element that wraps radio-buttons\n\nThe following state attributes are available for styling:\n\nAttribute  | Description | Part name\n-----------|-------------|------------\n`disabled` | Set when the radio group and its children are disabled. | :host\n`has-label` | Set when the element has a label | :host\n\nSee [ThemableMixin – how to apply styles for shadow parts](https://github.com/vaadin/vaadin-themable-mixin/wiki)",
+          "description": "`<vaadin-radio-group>` is a Polymer element for grouping vaadin-radio-buttons.\n\n```html\n<vaadin-radio-group>\n  <vaadin-radio-button name=\"foo\">Foo</vaadin-radio-button>\n  <vaadin-radio-button name=\"bar\">Bar</vaadin-radio-button>\n  <vaadin-radio-button name=\"baz\">Baz</vaadin-radio-button>\n</vaadin-radio-group>\n```\n\n### Styling\n\nThe following shadow DOM parts are available for styling:\n\nPart name | Description\n----------------|----------------\n`label` | The label element\n\nThe following state attributes are available for styling:\n\nAttribute  | Description | Part name\n-----------|-------------|------------\n`disabled` | Set when the radio group and its children are disabled. | :host\n`has-label` | Set when the element has a label | :host\n\nSee [ThemableMixin – how to apply styles for shadow parts](https://github.com/vaadin/vaadin-themable-mixin/wiki)",
           "summary": "",
-          "path": "src/vaadin-radio-group.html",
+          "path": "src/vaadin-field.html",
           "properties": [
             {
               "name": "_radioButtons",
@@ -1465,11 +1786,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 164,
+                  "line": 136,
                   "column": 8
                 },
                 "end": {
-                  "line": 166,
+                  "line": 138,
                   "column": 9
                 }
               },
@@ -1486,11 +1807,11 @@
               "privacy": "public",
               "sourceRange": {
                 "start": {
-                  "line": 95,
+                  "line": 67,
                   "column": 12
                 },
                 "end": {
-                  "line": 99,
+                  "line": 71,
                   "column": 13
                 }
               },
@@ -1508,11 +1829,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 101,
+                  "line": 73,
                   "column": 12
                 },
                 "end": {
-                  "line": 104,
+                  "line": 76,
                   "column": 13
                 }
               },
@@ -1530,11 +1851,11 @@
               "privacy": "public",
               "sourceRange": {
                 "start": {
-                  "line": 109,
+                  "line": 81,
                   "column": 12
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                 "end": {
-                  "line": 113,
+                  "line": 85,
                   "column": 13
                 }
               },
@@ -1553,11 +1874,11 @@
               "privacy": "public",
               "sourceRange": {
                 "start": {
-                  "line": 118,
+                  "line": 90,
                   "column": 12
                 },
                 "end": {
-                  "line": 122,
+                  "line": 94,
                   "column": 13
                 }
               },
@@ -1577,11 +1898,11 @@
               "privacy": "private",
               "sourceRange": {
                 "start": {
-                  "line": 129,
+                  "line": 101,
                   "column": 8
                 },
                 "end": {
-                  "line": 150,
+                  "line": 122,
                   "column": 9
                 }
               },
@@ -1597,11 +1918,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 152,
+                  "line": 124,
                   "column": 8
                 },
                 "end": {
-                  "line": 162,
+                  "line": 134,
                   "column": 9
                 }
               },
@@ -1617,11 +1938,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 168,
+                  "line": 140,
                   "column": 8
                 },
                 "end": {
-                  "line": 171,
+                  "line": 143,
                   "column": 9
                 }
               },
@@ -1638,11 +1959,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 173,
+                  "line": 145,
                   "column": 8
                 },
                 "end": {
-                  "line": 177,
+                  "line": 149,
                   "column": 9
                 }
               },
@@ -1662,11 +1983,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 179,
+                  "line": 151,
                   "column": 8
                 },
                 "end": {
-                  "line": 199,
+                  "line": 171,
                   "column": 9
                 }
               },
@@ -1682,11 +2003,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 201,
+                  "line": 173,
                   "column": 8
                 },
                 "end": {
-                  "line": 209,
+                  "line": 181,
                   "column": 9
                 }
               },
@@ -1709,11 +2030,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 211,
+                  "line": 183,
                   "column": 8
                 },
                 "end": {
-                  "line": 216,
+                  "line": 188,
                   "column": 9
                 }
               },
@@ -1726,11 +2047,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 218,
+                  "line": 190,
                   "column": 8
                 },
                 "end": {
-                  "line": 220,
+                  "line": 192,
                   "column": 9
                 }
               },
@@ -1743,11 +2064,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 222,
+                  "line": 194,
                   "column": 8
                 },
                 "end": {
-                  "line": 234,
+                  "line": 206,
                   "column": 9
                 }
               },
@@ -1767,11 +2088,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 236,
+                  "line": 208,
                   "column": 8
                 },
                 "end": {
-                  "line": 248,
+                  "line": 220,
                   "column": 9
                 }
               },
@@ -1791,11 +2112,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 250,
+                  "line": 222,
                   "column": 8
                 },
                 "end": {
-                  "line": 254,
+                  "line": 226,
                   "column": 9
                 }
               },
@@ -1815,11 +2136,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 256,
+                  "line": 228,
                   "column": 8
                 },
                 "end": {
-                  "line": 260,
+                  "line": 232,
                   "column": 9
                 }
               },
@@ -1839,11 +2160,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 262,
+                  "line": 234,
                   "column": 8
                 },
                 "end": {
-                  "line": 272,
+                  "line": 244,
                   "column": 9
                 }
               },
@@ -1866,11 +2187,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 274,
+                  "line": 246,
                   "column": 8
                 },
                 "end": {
-                  "line": 277,
+                  "line": 249,
                   "column": 9
                 }
               },
@@ -1890,11 +2211,11 @@
               "privacy": "protected",
               "sourceRange": {
                 "start": {
-                  "line": 279,
+                  "line": 251,
                   "column": 8
                 },
                 "end": {
-                  "line": 285,
+                  "line": 257,
                   "column": 9
                 }
               },
@@ -1997,11 +2318,11 @@
           "metadata": {},
           "sourceRange": {
             "start": {
-              "line": 85,
+              "line": 57,
               "column": 6
             },
             "end": {
-              "line": 287,
+              "line": 259,
               "column": 7
             }
           },
@@ -2014,11 +2335,11 @@
               "description": "The current disabled state of the radio group. True if group and all internal radio buttons are disabled.",
               "sourceRange": {
                 "start": {
-                  "line": 95,
+                  "line": 67,
                   "column": 12
                 },
                 "end": {
-                  "line": 99,
+                  "line": 71,
                   "column": 13
                 }
               },
@@ -2030,11 +2351,11 @@
               "description": "String used for the label element.",
               "sourceRange": {
                 "start": {
-                  "line": 109,
+                  "line": 81,
                   "column": 12
                 },
                 "end": {
-                  "line": 113,
+                  "line": 85,
                   "column": 13
                 }
               },
@@ -2046,11 +2367,11 @@
               "description": "Value of the radio group.",
               "sourceRange": {
                 "start": {
-                  "line": 118,
+                  "line": 90,
                   "column": 12
                 },
                 "end": {
-                  "line": 122,
+                  "line": 94,
                   "column": 13
                 }
               },
@@ -2076,12 +2397,12 @@
               "name": "",
               "range": {
                 "start": {
-                  "line": 42,
-                  "column": 8
+                  "line": 19,
+                  "column": 4
                 },
                 "end": {
-                  "line": 42,
-                  "column": 31
+                  "line": 19,
+                  "column": 27
                 }
               }
             }
diff --git a/demo/radio-group-demos.html b/demo/radio-group-demos.html
index f1401b3..48f3335 100644
--- a/demo/radio-group-demos.html
+++ b/demo/radio-group-demos.html
@@ -20,11 +20,12 @@ <h3>Radio Group</h3>
     <h3>Radio Group Disabled</h3>
     <vaadin-demo-snippet id="radio-group-demos-radio-group-disabled">
       <template preserve-content>
-        <vaadin-radio-group disabled>
+        <vaadin-radio-group label="Mark" disabled>
           <vaadin-radio-button>1</vaadin-radio-button>
           <vaadin-radio-button>2</vaadin-radio-button>
           <vaadin-radio-button>3</vaadin-radio-button>
           <vaadin-radio-button>4</vaadin-radio-button>
+          <vaadin-radio-button>5</vaadin-radio-button>
         </vaadin-radio-group>
       </template>
     </vaadin-demo-snippet>
@@ -45,16 +46,16 @@ <h3>Radio Group with Value</h3>
       </template>
     </vaadin-demo-snippet>
 
-    <h3>Radio Group with Iron Form</h3>
+    <h3>Radio Group with Validation in Iron Form</h3>
     <vaadin-demo-snippet id="radio-group-demos-radio-group-with-iron-form">
       <template preserve-content>
         <iron-form id="test-form">
           <form>
-            <vaadin-radio-group>
-              <vaadin-radio-button name="radio-group-first">1</vaadin-radio-button>
-              <vaadin-radio-button name="radio-group-second">2</vaadin-radio-button>
-              <vaadin-radio-button name="radio-group-third">3</vaadin-radio-button>
-              <vaadin-radio-button name="radio-group-fourth">4</vaadin-radio-button>
+            <vaadin-radio-group label="Complexity Level" required error-message="Please select an option">
+              <vaadin-radio-button name="complexity-one">1</vaadin-radio-button>
+              <vaadin-radio-button name="complexity-two">2</vaadin-radio-button>
+              <vaadin-radio-button name="complexity-three">3</vaadin-radio-button>
+              <vaadin-radio-button name="complexity-four">4</vaadin-radio-button>
             </vaadin-radio-group>
             <vaadin-button id="submit-button">Submit</vaadin-button>
           </form>
@@ -77,16 +78,16 @@ <h3>Radio Group with Iron Form</h3>
       </template>
     </vaadin-demo-snippet>
 
-    <h3>Radio Group with Iron Form with custom value</h3>
+    <h3>Radio Group with Custom Value Name in Iron Form</h3>
     <vaadin-demo-snippet id="radio-group-demos-radio-group-with-iron-form-with-custom-value">
       <template preserve-content>
         <iron-form id="test-form-custom-value">
           <form>
-            <vaadin-radio-group>
-              <vaadin-radio-button name="radio-group" value="first">1</vaadin-radio-button>
-              <vaadin-radio-button name="radio-group" value="second">2</vaadin-radio-button>
-              <vaadin-radio-button name="radio-group" value="third">3</vaadin-radio-button>
-              <vaadin-radio-button name="radio-group" value="fourth">4</vaadin-radio-button>
+            <vaadin-radio-group label="Complexity Level" required error-message="Please select an option">
+              <vaadin-radio-button name="complexity" value="1">1</vaadin-radio-button>
+              <vaadin-radio-button name="complexity" value="2">2</vaadin-radio-button>
+              <vaadin-radio-button name="complexity" value="3">3</vaadin-radio-button>
+              <vaadin-radio-button name="complexity" value="4">4</vaadin-radio-button>
             </vaadin-radio-group>
             <vaadin-button id="submit-button-custom-value">Submit</vaadin-button>
           </form>
diff --git a/src/vaadin-radio-group.html b/src/vaadin-radio-group.html
index e4337f9..d2937c8 100644
--- a/src/vaadin-radio-group.html
+++ b/src/vaadin-radio-group.html
@@ -43,8 +43,12 @@
         <slot id="slot"></slot>
       </div>
 
+      <div part="error-message"
+        id="[[_errorId]]"
+        aria-live="assertive"
+        aria-hidden$="[[_getErrorMessageAriaHidden(invalid, errorMessage, _errorId)]]"
+      >[[errorMessage]]</div>
     </div>
-
   </template>
 
   <script>
@@ -73,7 +77,9 @@
        *
        * Attribute  | Description | Part name
        * -----------|-------------|------------
-       * `disabled` | Set when the radio group and its children are disabled. | :host
+       * `disabled`   | Set when the radio group and its children are disabled. | :host
+       * `readonly` | Set to a readonly text field | :host
+       * `invalid` | Set when the element is invalid | :host
        * `has-label` | Set when the element has a label | :host
        *
        * See [ThemableMixin – how to apply styles for shadow parts](https://github.com/vaadin/vaadin-themable-mixin/wiki)
@@ -99,6 +105,45 @@
               observer: '_disabledChanged'
             },
 
+            /**
+             * This attribute indicates that the user cannot modify the value of the control.
+             */
+            readonly: {
+              type: Boolean,
+              reflectToAttribute: true,
+              observer: '_readonlyChanged'
+            },
+
+            /**
+             * This property is set to true when the value is invalid.
+             */
+            invalid: {
+              type: Boolean,
+              reflectToAttribute: true,
+              notify: true,
+              value: false
+            },
+
+            /**
+             * Specifies that the user must fill in a value.
+             */
+            required: {
+              type: Boolean,
+              reflectToAttribute: true
+            },
+
+            /**
+             * Error to show when the input value is invalid.
+             */
+            errorMessage: {
+              type: String,
+              value: ''
+            },
+
+            _errorId: {
+              type: String
+            },
+
             _checkedButton: {
               type: Object,
               observer: '_checkedButtonChanged'
@@ -160,6 +205,11 @@
           }
 
           this.setAttribute('role', 'radiogroup');
+
+          this.addEventListener('focusout', e => this.validate());
+
+          const uniqueId = RadioGroupElement._uniqueId = 1 + RadioGroupElement._uniqueId || 0;
+          this._errorId = `${this.constructor.is}-error-${uniqueId}`;
         }
 
         get _radioButtons() {
@@ -173,17 +223,31 @@
 
         _disabledChanged(disabled) {
           this.setAttribute('aria-disabled', disabled);
+          this._updateDisableButtons();
+        }
+
+        _updateDisableButtons() {
+          this._radioButtons.forEach(button => {
+            if (this.disabled) {
+              button.disabled = true;
+            } else if (this.readonly) {
+              // it's not possible to set readonly to radio buttons, but we can
+              // unchecked ones instead.
+              button.disabled = button !== this._checkedButton && this.readonly;
+            } else {
+              button.disabled = false;
+            }
+          });
+        }
 
-          this._radioButtons.forEach(button => button.disabled = disabled);
+        _readonlyChanged(newV, oldV) {
+          (newV || oldV) && this._updateDisableButtons();
         }
 
         _addActiveListeners() {
           this.addEventListener('keydown', e => {
             // if e.target is vaadin-radio-group then assign to checkedRadioButton currently checked radio button
             var checkedRadioButton = (e.target == this) ? this._checkedButton : e.target;
-            if (this.disabled) {
-              return;
-            }
 
             // LEFT, UP - select previous radio button
             if (e.keyCode === 37 || e.keyCode === 38) {
@@ -216,6 +280,7 @@
           return this.contains(activeElement);
         }
 
+
         _hasEnabledButtons() {
           return !this._radioButtons.every((button) => button.disabled);
         }
@@ -250,14 +315,14 @@
 
         _changeSelectedButton(button) {
           this._checkedButton = button;
-
+          this.readonly && this._updateDisableButtons();
           this._setFocusable(this._radioButtons.indexOf(button));
         }
 
         _checkedButtonChanged(checkedButton) {
           this._radioButtons.forEach(button => button.checked = button === checkedButton);
-
           this.value = checkedButton.value;
+          this.validate();
         }
 
         _valueChanged(newV, oldV) {
@@ -270,6 +335,30 @@
               console.warn(`No <vaadin-radio-button> with value ${newV} found.`);
             }
           }
+
+          if (newV !== '' && newV != null) {
+            this.setAttribute('has-value', '');
+          } else {
+            this.removeAttribute('has-value');
+          }
+        }
+
+        /**
+         * Returns true if `value` is valid.
+         * `<iron-form>` uses this to check the validity or all its elements.
+         *
+         * @return {boolean} True if the value is valid.
+         */
+        validate() {
+          return !(this.invalid = !this.checkValidity());
+        }
+
+        /**
+         * Returns true if the current input value satisfies all constraints (if any)
+         * @returns {boolean}
+         */
+        checkValidity() {
+          return !this.required || !!this.value;
         }
 
         _setFocusable(idx) {
@@ -285,6 +374,13 @@
           }
         }
 
+        _getActiveErrorId(invalid, errorMessage, errorId) {
+          return errorMessage && invalid ? errorId : undefined;
+        }
+
+        _getErrorMessageAriaHidden(invalid, errorMessage, errorId) {
+          return (!this._getActiveErrorId(invalid, errorMessage, errorId)).toString();
+        }
       }
 
       customElements.define(RadioGroupElement.is, RadioGroupElement);
diff --git a/test/vaadin-radio-group.html b/test/vaadin-radio-group.html
index 941e646..c88302d 100644
--- a/test/vaadin-radio-group.html
+++ b/test/vaadin-radio-group.html
@@ -35,12 +35,23 @@
 
   <script>
     describe('vaadin-radio-group', () => {
-      var vaadinRadioButtonGroup, vaadinRadioButtonList,
+
+      function blur(e) {
+        e.dispatchEvent(new CustomEvent('focusout', {bubbles: true, composed: true}));
+      }
+
+      function visible(e) {
+        const rect = e.getBoundingClientRect();
+        return !!(rect.width && rect.height);
+      }
+
+      var vaadinRadioButtonGroup, vaadinRadioButtonList, errorElement,
         buttonsListWithDisabled, groupWithDisabledButton;
 
       beforeEach(() => {
         vaadinRadioButtonGroup = fixture('default');
         vaadinRadioButtonList = vaadinRadioButtonGroup.querySelectorAll('vaadin-radio-button');
+        errorElement = vaadinRadioButtonGroup.shadowRoot.querySelector('[part="error-message"]');
 
         groupWithDisabledButton = fixture('with-disabled-button');
         buttonsListWithDisabled = groupWithDisabledButton.querySelectorAll('vaadin-radio-button');
@@ -107,6 +118,29 @@
         expect(vaadinRadioButtonList[2].checked).to.be.false;
       });
 
+      it('should check radio button with keyboard if not disabled or readonly', () => {
+        vaadinRadioButtonList[1].checked = true;
+
+        MockInteractions.keyDownOn(vaadinRadioButtonGroup, 39);
+        expect(vaadinRadioButtonList[2].checked).to.be.true;
+      });
+
+      it('should not check radio button with keyboard if disabled', () => {
+        vaadinRadioButtonList[1].checked = true;
+        vaadinRadioButtonGroup.disabled = true;
+
+        MockInteractions.keyDownOn(vaadinRadioButtonGroup, 39);
+        expect(vaadinRadioButtonList[2].checked).to.be.false;
+      });
+
+      it('should not check radio button with keyboard if readonly', () => {
+        vaadinRadioButtonList[1].checked = true;
+        vaadinRadioButtonGroup.readonly = true;
+
+        MockInteractions.keyDownOn(vaadinRadioButtonGroup, 39);
+        expect(vaadinRadioButtonList[2].checked).to.be.false;
+      });
+
       it('previous/last radio button should be focused and checked after left/up', () => {
         vaadinRadioButtonList[1].checked = true;
 
@@ -215,6 +249,94 @@
         expect(vaadinRadioButtonGroup.label).to.be.equal('foo');
       });
 
+      it('should disable unchecked buttons when readonly', () => {
+        vaadinRadioButtonGroup.readonly = true;
+        expect(vaadinRadioButtonList[0].disabled).to.be.true;
+        expect(vaadinRadioButtonList[1].disabled).to.be.true;
+        expect(vaadinRadioButtonList[2].disabled).to.be.true;
+
+        vaadinRadioButtonGroup.value = '2';
+        expect(vaadinRadioButtonList[0].disabled).to.be.true;
+        expect(vaadinRadioButtonList[1].disabled).to.be.false;
+        expect(vaadinRadioButtonList[2].disabled).to.be.true;
+
+        vaadinRadioButtonGroup.readonly = false;
+        expect(vaadinRadioButtonList[0].disabled).to.be.false;
+        expect(vaadinRadioButtonList[1].disabled).to.be.false;
+        expect(vaadinRadioButtonList[2].disabled).to.be.false;
+      });
+
+      it('should not have the has-value attribute by default', () => {
+        expect(vaadinRadioButtonGroup.hasAttribute('has-value')).to.be.false;
+      });
+
+      it('should change the has-value attribute on value', () => {
+        vaadinRadioButtonGroup.value = '2';
+        expect(vaadinRadioButtonGroup.hasAttribute('has-value')).to.be.true;
+
+        vaadinRadioButtonGroup.value = '';
+        expect(vaadinRadioButtonGroup.hasAttribute('has-value')).to.be.false;
+      });
+
+      it('should pass validation when field is not required', () => {
+        expect(vaadinRadioButtonGroup.checkValidity()).to.be.true;
+        expect(vaadinRadioButtonGroup.invalid).to.be.false;
+      });
+
+      it('should not set invalid when field is required and user has not blurred yet', () => {
+        vaadinRadioButtonGroup.required = true;
+        expect(vaadinRadioButtonGroup.checkValidity()).to.be.false;
+        expect(vaadinRadioButtonGroup.invalid).to.be.false;
+      });
+
+      it('validate method should set invalid', () => {
+        vaadinRadioButtonGroup.required = true;
+        vaadinRadioButtonGroup.validate();
+        expect(vaadinRadioButtonGroup.invalid).to.be.true;
+      });
+
+      it('should validate after changing selected option', () => {
+        vaadinRadioButtonGroup.required = true;
+        vaadinRadioButtonGroup.validate();
+
+        vaadinRadioButtonList[1].checked = true;
+        expect(vaadinRadioButtonGroup.invalid).to.be.false;
+      });
+
+      it('should pass validation and set invalid when field is required and user blurs', () => {
+        vaadinRadioButtonGroup.required = true;
+        blur(vaadinRadioButtonGroup);
+        expect(vaadinRadioButtonGroup.checkValidity()).to.be.false;
+        expect(vaadinRadioButtonGroup.invalid).to.be.true;
+      });
+
+      it('error should have appropriate aria attributes and id', () => {
+        expect(errorElement.getAttribute('aria-live')).to.be.equal('assertive');
+        expect(errorElement.getAttribute('aria-hidden')).to.be.equal('true');
+        expect(/^vaadin-radio-group-error-\d+$/.test(errorElement.id)).to.be.true;
+      });
+
+      it('should remove aria-hidden when error is shown', () => {
+        vaadinRadioButtonGroup.errorMessage = 'Bad input!';
+        vaadinRadioButtonGroup.invalid = true;
+        expect(errorElement.getAttribute('aria-hidden')).to.be.equal('false');
+      });
+
+      it('should hide error message by default', () => {
+        vaadinRadioButtonGroup.errorMessage = 'Bad input!';
+        expect(visible(errorElement)).to.be.false;
+      });
+
+      it('should show error message on invalid', done => {
+        vaadinRadioButtonGroup.required = true;
+        vaadinRadioButtonGroup.errorMessage = 'Bad input!';
+        blur(vaadinRadioButtonGroup);
+
+        Polymer.Base.async(() => {
+          expect(visible(errorElement)).to.be.true;
+          done();
+        }, 100);
+      });
     });
   </script>
 </body>
diff --git a/test/visual/default.html b/test/visual/default.html
index 3709079..fd95086 100644
--- a/test/visual/default.html
+++ b/test/visual/default.html
@@ -16,6 +16,13 @@
       <vaadin-radio-button disabled>2</vaadin-radio-button>
       <vaadin-radio-button>3</vaadin-radio-button>
     </vaadin-radio-group>
+
+    <br/>
+
+    <vaadin-radio-group label="Label" error-message='Error message' invalid>
+      <vaadin-radio-button checked>1</vaadin-radio-button>
+      <vaadin-radio-button>2</vaadin-radio-button>
+    </vaadin-radio-group>
   </div>
 
 </body>
diff --git a/test/visual/screens/vaadin-radio-button/default-tests/default/chrome.png b/test/visual/screens/vaadin-radio-button/default-tests/default/chrome.png
index ae2c636..cca1ebb 100644
Binary files a/test/visual/screens/vaadin-radio-button/default-tests/default/chrome.png and b/test/visual/screens/vaadin-radio-button/default-tests/default/chrome.png differ
diff --git a/test/visual/screens/vaadin-radio-button/default-tests/default/firefox.png b/test/visual/screens/vaadin-radio-button/default-tests/default/firefox.png
index d0a64a9..067213a 100644
Binary files a/test/visual/screens/vaadin-radio-button/default-tests/default/firefox.png and b/test/visual/screens/vaadin-radio-button/default-tests/default/firefox.png differ
diff --git a/theme/lumo/vaadin-radio-group-styles.html b/theme/lumo/vaadin-radio-group-styles.html
index 8e467d7..b8bb982 100644
--- a/theme/lumo/vaadin-radio-group-styles.html
+++ b/theme/lumo/vaadin-radio-group-styles.html
@@ -55,6 +55,29 @@
       :host([invalid]) [part="label"] {
         color: var(--lumo-error-text-color);
       }
+
+      [part="error-message"] {
+        margin-left: calc(var(--lumo-border-radius) / 4);
+        font-size: var(--lumo-font-size-xs);
+        line-height: var(--lumo-line-height-xs);
+        color: var(--lumo-error-text-color);
+        will-change: max-height;
+        transition: 0.4s max-height;
+        max-height: 5em;
+      }
+
+      /* Margin that doesn’t reserve space when there’s no error message */
+      [part="error-message"]:not(:empty)::before,
+      [part="error-message"]:not(:empty)::after {
+        content: "";
+        display: block;
+        height: 0.4em;
+      }
+
+      :host(:not([invalid])) [part="error-message"] {
+        max-height: 0;
+        overflow: hidden;
+      }
     </style>
   </template>
 </dom-module>
diff --git a/theme/material/vaadin-radio-group-styles.html b/theme/material/vaadin-radio-group-styles.html
index 4911c2e..20b824d 100644
--- a/theme/material/vaadin-radio-group-styles.html
+++ b/theme/material/vaadin-radio-group-styles.html
@@ -62,6 +62,23 @@
       :host([invalid]) [part="label"] {
         color: var(--material-error-text-color);
       }
+
+      [part="error-message"] {
+        font-size: .75em;
+        line-height: 1;
+        color: var(--material-error-text-color);
+        margin-top: 6px;
+      }
+
+      :host(:not([invalid])) [part="error-message"] {
+        margin-top: 0;
+        max-height: 0;
+        overflow: hidden;
+      }
+
+      :host([invalid]) [part="error-message"] {
+        animation: reveal 0.2s;
+      }
     </style>
   </template>
 </dom-module>