diff --git a/index.d.ts b/index.d.ts
index 56d0da53877..e2557e2e8a2 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -1,6 +1,7 @@
 declare module '@primer/components' {
   type Omit<T, K> = Pick<T, Exclude<keyof T, K>>
   import * as StyledSystem from 'styled-system'
+  import * as StyledSystemProps from '@styled-system/prop-types'
   import * as StyledComponents from 'styled-components'
   import * as History from 'history'
 
@@ -11,7 +12,7 @@ declare module '@primer/components' {
     to?: History.LocationDescriptor
   }
 
-  interface CommonProps extends BaseProps, StyledSystem.ColorProps, StyledSystem.SpaceProps {}
+  interface CommonProps extends BaseProps, StyledSystemProps.color, StyledSystemProps.space {}
 
   interface LayoutProps
     extends BaseProps,
@@ -60,11 +61,14 @@ declare module '@primer/components' {
       StyledSystem.AlignSelfProps,
       StyledSystem.OrderProps {}
 
-  interface FlexContainerProps
+  interface FlexProps
     extends BaseProps,
       CommonProps,
       LayoutProps,
-      FlexItemProps,
+      StyledSystem.FlexProps,
+      StyledSystem.JustifySelfProps,
+      StyledSystem.AlignSelfProps,
+      StyledSystem.OrderProps,
       StyledSystem.FlexBasisProps,
       StyledSystem.FlexDirectionProps,
       StyledSystem.FlexWrapProps,
@@ -73,10 +77,6 @@ declare module '@primer/components' {
       StyledSystem.JustifyContentProps,
       StyledSystem.JustifyItemsProps {}
 
-  export interface FlexProps
-    extends FlexContainerProps,
-      Omit<React.HTMLProps<HTMLDivElement>, keyof FlexContainerProps> {}
-
   export const Flex: React.FunctionComponent<FlexProps> & {
     Item: React.FunctionComponent<FlexItemProps>
   }
@@ -237,6 +237,18 @@ declare module '@primer/components' {
 
   export const StateLabel: React.FunctionComponent<StateLabelProps>
 
+  export interface TabNavProps extends CommonProps {
+    'aria-label'?: string
+  }
+
+  export interface TabNavItemProps extends CommonProps {
+    selected?: boolean
+  }
+
+  export const TabNav: React.FunctionComponent<TabNavProps> & {
+    Item: React.FunctionComponent<TabNavItemProps>
+  }
+
   export interface TextInputProps extends CommonProps {
     autocomplete?: string
     'aria-label'?: string
@@ -272,9 +284,23 @@ declare module '@primer/components' {
     label?: string
   }
 
-  export const UnderlineNav: React.FunctionComponent<UnderlineNavProps>
+  export interface UnderlineNavItemProps extends CommonProps {
+    selected?: boolean
+  }
+
+  export const UnderlineNav: React.FunctionComponent<UnderlineNavProps> & {
+    Item: React.FunctionComponent<UnderlineNavItemProps>
+  }
 
   export const theme: Object
+
+  export interface DialogProps extends CommonProps {
+    title: string
+    isOpen: boolean
+    onDismiss: () => unknown
+  }
+
+  export const Dialog: React.FunctionComponent<DialogProps>
 }
 
 declare module '@primer/components/src/Box' {
@@ -404,6 +430,10 @@ declare module '@primer/components/src/StateLabel' {
   import {StateLabel} from '@primer/components'
   export default StateLabel
 }
+declare module '@primer/components/src/TabNav' {
+  import {TabNav} from '@primer/components'
+  export default TabNav
+}
 declare module '@primer/components/src/TextInput' {
   import {TextInput} from '@primer/components'
   export default TextInput
@@ -420,3 +450,7 @@ declare module '@primer/components/src/theme' {
   import {theme} from '@primer/components'
   export default theme
 }
+declare module '@primer/components/src/Dialog' {
+  import {Dialog} from '@primer/components'
+  export default Dialog
+}
diff --git a/package-lock.json b/package-lock.json
index a3aa4b8a1bb..2a3b9041096 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "@primer/components",
-  "version": "13.2.0",
+  "version": "13.4.0",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
@@ -905,6 +905,17 @@
       "integrity": "sha512-h4t4jFjtm1YV7UirAFuSuFGyLa+NNxjdkq6DpFLANNQY5rHueFZHVY+8Cu1HYVP6DrheB0kv4m5xPjo7eKT7yQ==",
       "dev": true
     },
+    "@jest/types": {
+      "version": "24.9.0",
+      "resolved": "https://registry.npmjs.org/@jest/types/-/types-24.9.0.tgz",
+      "integrity": "sha512-XKK7ze1apu5JWQ5eZjHITP66AX+QsLlbaJRBGYr8pNzwcAE2JVkwnf0yqjHTsDRcjR0mujy/NmZMXw5kl+kGBw==",
+      "dev": true,
+      "requires": {
+        "@types/istanbul-lib-coverage": "^2.0.0",
+        "@types/istanbul-reports": "^1.1.1",
+        "@types/yargs": "^13.0.0"
+      }
+    },
     "@mdx-js/loader": {
       "version": "0.15.0",
       "resolved": "https://registry.npmjs.org/@mdx-js/loader/-/loader-0.15.0.tgz",
@@ -992,6 +1003,12 @@
       "resolved": "https://registry.npmjs.org/@reach/utils/-/utils-0.2.3.tgz",
       "integrity": "sha512-zM9rA8jDchr05giMhL95dPeYkK67cBQnIhCVrOKKqgWGsv+2GE/HZqeptvU4zqs0BvIqsThwov+YxVNVh5csTQ=="
     },
+    "@sheerun/mutationobserver-shim": {
+      "version": "0.3.2",
+      "resolved": "https://registry.npmjs.org/@sheerun/mutationobserver-shim/-/mutationobserver-shim-0.3.2.tgz",
+      "integrity": "sha512-vTCdPp/T/Q3oSqwHmZ5Kpa9oI7iLtGl3RQaA/NyLHikvcrPxACkkKVr/XzkSPJWXHRhKGzVvb0urJsbMlRxi1Q==",
+      "dev": true
+    },
     "@styled-system/background": {
       "version": "5.0.5",
       "resolved": "https://registry.npmjs.org/@styled-system/background/-/background-5.0.5.tgz",
@@ -1197,18 +1214,151 @@
         }
       }
     },
+    "@testing-library/dom": {
+      "version": "5.6.1",
+      "resolved": "https://registry.npmjs.org/@testing-library/dom/-/dom-5.6.1.tgz",
+      "integrity": "sha512-Y1T2bjtvQMewffn1CJ28kpgnuvPYKsBcZMagEH0ppfEMZPDc8AkkEnTk4smrGZKw0cblNB3lhM2FMnpfLExlHg==",
+      "dev": true,
+      "requires": {
+        "@babel/runtime": "^7.5.5",
+        "@sheerun/mutationobserver-shim": "^0.3.2",
+        "aria-query": "3.0.0",
+        "pretty-format": "^24.8.0",
+        "wait-for-expect": "^1.2.0"
+      },
+      "dependencies": {
+        "@babel/runtime": {
+          "version": "7.5.5",
+          "resolved": "https://registry.npmjs.org/@babel/runtime/-/runtime-7.5.5.tgz",
+          "integrity": "sha512-28QvEGyQyNkB0/m2B4FU7IEZGK2NUrcMtT6BZEFALTguLk+AUT6ofsHtPk5QyjAdUkpMJ+/Em+quwz4HOt30AQ==",
+          "dev": true,
+          "requires": {
+            "regenerator-runtime": "^0.13.2"
+          }
+        },
+        "ansi-regex": {
+          "version": "4.1.0",
+          "resolved": "https://registry.npmjs.org/ansi-regex/-/ansi-regex-4.1.0.tgz",
+          "integrity": "sha512-1apePfXM1UOSqw0o9IiFAovVz9M5S1Dg+4TrDwfMewQ6p/rmMueb7tWZjQ1rx4Loy1ArBggoqGpfqqdI4rondg==",
+          "dev": true
+        },
+        "aria-query": {
+          "version": "3.0.0",
+          "resolved": "https://registry.npmjs.org/aria-query/-/aria-query-3.0.0.tgz",
+          "integrity": "sha1-ZbP8wcoRVajJrmTW7uKX8V1RM8w=",
+          "dev": true,
+          "requires": {
+            "ast-types-flow": "0.0.7",
+            "commander": "^2.11.0"
+          }
+        },
+        "pretty-format": {
+          "version": "24.9.0",
+          "resolved": "https://registry.npmjs.org/pretty-format/-/pretty-format-24.9.0.tgz",
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+          "dev": true,
+          "requires": {
+            "@jest/types": "^24.9.0",
+            "ansi-regex": "^4.0.0",
+            "ansi-styles": "^3.2.0",
+            "react-is": "^16.8.4"
+          }
+        },
+        "regenerator-runtime": {
+          "version": "0.13.3",
+          "resolved": "https://registry.npmjs.org/regenerator-runtime/-/regenerator-runtime-0.13.3.tgz",
+          "integrity": "sha512-naKIZz2GQ8JWh///G7L3X6LaQUAMp2lvb1rvwwsURe/VXwD6VMfr+/1NuNw3ag8v2kY1aQ/go5SNn79O9JU7yw==",
+          "dev": true
+        }
+      }
+    },
+    "@testing-library/react": {
+      "version": "8.0.6",
+      "resolved": "https://registry.npmjs.org/@testing-library/react/-/react-8.0.6.tgz",
+      "integrity": "sha512-/4oeS0eatnHvAf9yuxIg1/8pjl1OrtWN7SLpDFEdxFjllIAEL09xXhA88C93vvlN+8enZa+xlXJ8ecohECT6Yg==",
+      "dev": true,
+      "requires": {
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+        "@testing-library/dom": "^5.5.4"
+      },
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+          "dev": true,
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+          }
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+          "resolved": "https://registry.npmjs.org/regenerator-runtime/-/regenerator-runtime-0.13.3.tgz",
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+          "dev": true
+        }
+      }
+    },
     "@types/estree": {
       "version": "0.0.39",
       "resolved": "https://registry.npmjs.org/@types/estree/-/estree-0.0.39.tgz",
       "integrity": "sha512-EYNwp3bU+98cpU4lAWYYL7Zz+2gryWH1qbdDTidVd6hkiR6weksdbMadyXKXNPEkQFhXM+hVO9ZygomHXp+AIw==",
       "dev": true
     },
+    "@types/istanbul-lib-coverage": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/@types/istanbul-lib-coverage/-/istanbul-lib-coverage-2.0.1.tgz",
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+      "dev": true
+    },
+    "@types/istanbul-lib-report": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/@types/istanbul-lib-report/-/istanbul-lib-report-1.1.1.tgz",
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+      "dev": true,
+      "requires": {
+        "@types/istanbul-lib-coverage": "*"
+      }
+    },
+    "@types/istanbul-reports": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/@types/istanbul-reports/-/istanbul-reports-1.1.1.tgz",
+      "integrity": "sha512-UpYjBi8xefVChsCoBpKShdxTllC9pwISirfoZsUa2AAdQg/Jd2KQGtSbw+ya7GPo7x/wAPlH6JBhKhAsXUEZNA==",
+      "dev": true,
+      "requires": {
+        "@types/istanbul-lib-coverage": "*",
+        "@types/istanbul-lib-report": "*"
+      }
+    },
     "@types/node": {
       "version": "10.11.0",
       "resolved": "https://registry.npmjs.org/@types/node/-/node-10.11.0.tgz",
       "integrity": "sha512-R4Dvw6KjSYn/SpvjRchBOwXr14vVVcFXCtnM3f0aLvlJS8a599rrcEoihcP2/+Z/f75E5GNPd4aWM7j1yei9og==",
       "dev": true
     },
+    "@types/styled-system": {
+      "version": "5.1.1",
+      "resolved": "https://registry.npmjs.org/@types/styled-system/-/styled-system-5.1.1.tgz",
+      "integrity": "sha512-RAF9Erif51vbD1ZbIiGN4ZrgxpSr44iMXrPjQK5+tI7PWLDugKepTWj7T/LqG5VfaYYIrEmOCzIpulhv+/D/XQ==",
+      "requires": {
+        "csstype": "^2.6.4"
+      }
+    },
+    "@types/yargs": {
+      "version": "13.0.2",
+      "resolved": "https://registry.npmjs.org/@types/yargs/-/yargs-13.0.2.tgz",
+      "integrity": "sha512-lwwgizwk/bIIU+3ELORkyuOgDjCh7zuWDFqRtPPhhVgq9N1F7CvLNKg1TX4f2duwtKQ0p044Au9r1PLIXHrIzQ==",
+      "dev": true,
+      "requires": {
+        "@types/yargs-parser": "*"
+      }
+    },
+    "@types/yargs-parser": {
+      "version": "13.0.0",
+      "resolved": "https://registry.npmjs.org/@types/yargs-parser/-/yargs-parser-13.0.0.tgz",
+      "integrity": "sha512-wBlsw+8n21e6eTd4yVv8YD/E3xq0O6nNnJIquutAsFGE7EyMKz7W6RNT6BRu1SmdgmlCZ9tb0X+j+D6HGr8pZw==",
+      "dev": true
+    },
     "@webassemblyjs/ast": {
       "version": "1.7.8",
       "resolved": "https://registry.npmjs.org/@webassemblyjs/ast/-/ast-1.7.8.tgz",
@@ -3578,17 +3728,29 @@
       "dev": true
     },
     "cheerio": {
-      "version": "1.0.0-rc.2",
-      "resolved": "https://registry.npmjs.org/cheerio/-/cheerio-1.0.0-rc.2.tgz",
-      "integrity": "sha1-S59TqBsn5NXawxwP/Qz6A8xoMNs=",
+      "version": "1.0.0-rc.3",
+      "resolved": "https://registry.npmjs.org/cheerio/-/cheerio-1.0.0-rc.3.tgz",
+      "integrity": "sha512-0td5ijfUPuubwLUu0OBoe98gZj8C/AA+RW3v67GPlGOrvxWjZmBXiBCRU+I8VEiNyJzjth40POfHiz2RB3gImA==",
       "dev": true,
       "requires": {
         "css-select": "~1.2.0",
-        "dom-serializer": "~0.1.0",
+        "dom-serializer": "~0.1.1",
         "entities": "~1.1.1",
         "htmlparser2": "^3.9.1",
         "lodash": "^4.15.0",
         "parse5": "^3.0.1"
+      },
+      "dependencies": {
+        "dom-serializer": {
+          "version": "0.1.1",
+          "resolved": "https://registry.npmjs.org/dom-serializer/-/dom-serializer-0.1.1.tgz",
+          "integrity": "sha512-l0IU0pPzLWSHBcieZbpOKgkIn3ts3vAh7ZuFyXNwJxJXk/c4Gwj9xaTJwIDVQCXawWD0qb3IzMGH5rglQaO0XA==",
+          "dev": true,
+          "requires": {
+            "domelementtype": "^1.3.0",
+            "entities": "^1.1.1"
+          }
+        }
       }
     },
     "chokidar": {
@@ -3791,12 +3953,6 @@
       "integrity": "sha1-p9BVi9icQveV3UIyj3QIMcpTvCU=",
       "dev": true
     },
-    "colors": {
-      "version": "0.5.1",
-      "resolved": "https://registry.npmjs.org/colors/-/colors-0.5.1.tgz",
-      "integrity": "sha1-fQAj6usVTo7p/Oddy5I9DtFmd3Q=",
-      "dev": true
-    },
     "combined-stream": {
       "version": "1.0.7",
       "resolved": "https://registry.npmjs.org/combined-stream/-/combined-stream-1.0.7.tgz",
@@ -4313,6 +4469,11 @@
         "cssom": "0.3.x"
       }
     },
+    "csstype": {
+      "version": "2.6.6",
+      "resolved": "https://registry.npmjs.org/csstype/-/csstype-2.6.6.tgz",
+      "integrity": "sha512-RpFbQGUE74iyPgvr46U9t1xoQBM8T4BL8SxrN66Le2xYAPSaDJJKeztV3awugusb3g3G9iL8StmkBBXhcbbXhg=="
+    },
     "currently-unhandled": {
       "version": "0.4.1",
       "resolved": "https://registry.npmjs.org/currently-unhandled/-/currently-unhandled-0.4.1.tgz",
@@ -4840,18 +5001,20 @@
       "dev": true
     },
     "enzyme": {
-      "version": "3.5.1",
-      "resolved": "https://registry.npmjs.org/enzyme/-/enzyme-3.5.1.tgz",
-      "integrity": "sha512-nRC9k3BbkcsZvheCfsbDH4SwG7pjhqv6SOwb1/pfR85WhLUcfG9zEJLId/8RAiDNNiDc+unlwMnN6kywlYucAg==",
+      "version": "3.10.0",
+      "resolved": "https://registry.npmjs.org/enzyme/-/enzyme-3.10.0.tgz",
+      "integrity": "sha512-p2yy9Y7t/PFbPoTvrWde7JIYB2ZyGC+NgTNbVEGvZ5/EyoYSr9aG/2rSbVvyNvMHEhw9/dmGUJHWtfQIEiX9pg==",
       "dev": true,
       "requires": {
         "array.prototype.flat": "^1.2.1",
         "cheerio": "^1.0.0-rc.2",
         "function.prototype.name": "^1.1.0",
         "has": "^1.0.3",
+        "html-element-map": "^1.0.0",
         "is-boolean-object": "^1.0.0",
         "is-callable": "^1.1.4",
         "is-number-object": "^1.0.3",
+        "is-regex": "^1.0.4",
         "is-string": "^1.0.4",
         "is-subset": "^0.1.1",
         "lodash.escape": "^4.0.1",
@@ -7338,6 +7501,23 @@
       "integrity": "sha1-wc56MWjIxmFAM6S194d/OyJfnDg=",
       "dev": true
     },
+    "html-element-map": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/html-element-map/-/html-element-map-1.1.0.tgz",
+      "integrity": "sha512-iqiG3dTZmy+uUaTmHarTL+3/A2VW9ox/9uasKEZC+R/wAtUrTcRlXPSaPqsnWPfIu8wqn09jQNwMRqzL54jSYA==",
+      "dev": true,
+      "requires": {
+        "array-filter": "^1.0.0"
+      },
+      "dependencies": {
+        "array-filter": {
+          "version": "1.0.0",
+          "resolved": "https://registry.npmjs.org/array-filter/-/array-filter-1.0.0.tgz",
+          "integrity": "sha1-uveeYubvTCpMC4MSMtr/7CUfnYM=",
+          "dev": true
+        }
+      }
+    },
     "html-encoding-sniffer": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/html-encoding-sniffer/-/html-encoding-sniffer-1.0.2.tgz",
@@ -7360,47 +7540,49 @@
       "dev": true
     },
     "htmlparser2": {
-      "version": "3.9.2",
-      "resolved": "https://registry.npmjs.org/htmlparser2/-/htmlparser2-3.9.2.tgz",
-      "integrity": "sha1-G9+HrMoPP55T+k/M6w9LTLsAszg=",
+      "version": "3.10.1",
+      "resolved": "https://registry.npmjs.org/htmlparser2/-/htmlparser2-3.10.1.tgz",
+      "integrity": "sha512-IgieNijUMbkDovyoKObU1DUhm1iwNYE/fuifEoEHfd1oZKZDaONBSkal7Y01shxsM49R4XaMdGez3WnF9UfiCQ==",
       "dev": true,
       "requires": {
-        "domelementtype": "^1.3.0",
+        "domelementtype": "^1.3.1",
         "domhandler": "^2.3.0",
         "domutils": "^1.5.1",
         "entities": "^1.1.1",
         "inherits": "^2.0.1",
-        "readable-stream": "^2.0.2"
+        "readable-stream": "^3.1.1"
       },
       "dependencies": {
-        "isarray": {
-          "version": "1.0.0",
-          "resolved": "https://registry.npmjs.org/isarray/-/isarray-1.0.0.tgz",
-          "integrity": "sha1-u5NdSFgsuhaMBoNJV6VKPgcSTxE=",
+        "domelementtype": {
+          "version": "1.3.1",
+          "resolved": "https://registry.npmjs.org/domelementtype/-/domelementtype-1.3.1.tgz",
+          "integrity": "sha512-BSKB+TSpMpFI/HOxCNr1O8aMOTZ8hT3pM3GQ0w/mWRmkhEDSFJkkyzz4XQsBV44BChwGkrDfMyjVD0eA2aFV3w==",
           "dev": true
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         "readable-stream": {
-          "version": "2.3.6",
-          "resolved": "http://registry.npmjs.org/readable-stream/-/readable-stream-2.3.6.tgz",
-          "integrity": "sha512-tQtKA9WIAhBF3+VLAseyMqZeBjW0AHJoxOtYqSUZNJxauErmLbVm2FW1y+J/YA9dUrAC39ITejlZWhVIwawkKw==",
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+          "resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-3.4.0.tgz",
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-            "inherits": "~2.0.3",
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-            "safe-buffer": "~5.1.1",
-            "string_decoder": "~1.1.1",
-            "util-deprecate": "~1.0.1"
+            "inherits": "^2.0.3",
+            "string_decoder": "^1.1.1",
+            "util-deprecate": "^1.0.1"
           }
         },
+        "safe-buffer": {
+          "version": "5.2.0",
+          "resolved": "https://registry.npmjs.org/safe-buffer/-/safe-buffer-5.2.0.tgz",
+          "integrity": "sha512-fZEwUGbVl7kouZs1jCdMLdt95hdIv0ZeHg6L7qPeciMZhZ+/gdesW4wgTARkrFWEpspjEATAzUGPG8N2jJiwbg==",
+          "dev": true
+        },
         "string_decoder": {
-          "version": "1.1.1",
-          "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-1.1.1.tgz",
-          "integrity": "sha512-n/ShnvDi6FHbbVfviro+WojiFzv+s8MPMHBczVePfUpDJLwoLT0ht1l4YwBCbi8pJAveEEdnkHyPyTP/mzRfwg==",
+          "version": "1.3.0",
+          "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-1.3.0.tgz",
+          "integrity": "sha512-hkRX8U1WjJFd8LsDJ2yQ/wWWxaopEsABU1XfkM8A+j0+85JAGppt16cr1Whg6KIbb4okU6Mql6BOj+uup/wKeA==",
           "dev": true,
           "requires": {
-            "safe-buffer": "~5.1.0"
+            "safe-buffer": "~5.2.0"
           }
         }
       }
@@ -10294,16 +10476,24 @@
       "dev": true
     },
     "nearley": {
-      "version": "2.15.1",
-      "resolved": "https://registry.npmjs.org/nearley/-/nearley-2.15.1.tgz",
-      "integrity": "sha512-8IUY/rUrKz2mIynUGh8k+tul1awMKEjeHHC5G3FHvvyAW6oq4mQfNp2c0BMea+sYZJvYcrrM6GmZVIle/GRXGw==",
+      "version": "2.18.0",
+      "resolved": "https://registry.npmjs.org/nearley/-/nearley-2.18.0.tgz",
+      "integrity": "sha512-/zQOMCeJcioI0xJtd5RpBiWw2WP7wLe6vq8/3Yu0rEwgus/G/+pViX80oA87JdVgjRt2895mZSv2VfZmy4W1uw==",
       "dev": true,
       "requires": {
+        "commander": "^2.19.0",
         "moo": "^0.4.3",
-        "nomnom": "~1.6.2",
         "railroad-diagrams": "^1.0.0",
         "randexp": "0.4.6",
         "semver": "^5.4.1"
+      },
+      "dependencies": {
+        "commander": {
+          "version": "2.20.0",
+          "resolved": "https://registry.npmjs.org/commander/-/commander-2.20.0.tgz",
+          "integrity": "sha512-7j2y+40w61zy6YC2iRNpUe/NwhNyoXrYpHMrSunaMG64nRnaf96zO/KMQR4OyN/UnE5KLyEBnKHd4aG3rskjpQ==",
+          "dev": true
+        }
       }
     },
     "neo-async": {
@@ -10856,16 +11046,6 @@
         }
       }
     },
-    "nomnom": {
-      "version": "1.6.2",
-      "resolved": "https://registry.npmjs.org/nomnom/-/nomnom-1.6.2.tgz",
-      "integrity": "sha1-hKZqJgF0QI/Ft3oY+IjszET7aXE=",
-      "dev": true,
-      "requires": {
-        "colors": "0.5.x",
-        "underscore": "~1.4.4"
-      }
-    },
     "nopt": {
       "version": "3.0.6",
       "resolved": "https://registry.npmjs.org/nopt/-/nopt-3.0.6.tgz",
@@ -11004,6 +11184,12 @@
       "integrity": "sha1-CqYOyZiaCz7Xlc9NBvYs8a1lObY=",
       "dev": true
     },
+    "object-keys": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/object-keys/-/object-keys-1.1.1.tgz",
+      "integrity": "sha512-NuAESUOUMrlIXOfHKzD6bpPu3tYt3xvjNdRIQ+FeT0lNb4K8WR70CaDxhuNguS2XG+GjkyMwOzsN5ZktImfhLA==",
+      "dev": true
+    },
     "object-visit": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/object-visit/-/object-visit-1.0.1.tgz",
@@ -11034,15 +11220,15 @@
       }
     },
     "object.entries": {
-      "version": "1.0.4",
-      "resolved": "https://registry.npmjs.org/object.entries/-/object.entries-1.0.4.tgz",
-      "integrity": "sha1-G/mk3SKI9bM/Opk9JXZh8F0WGl8=",
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/object.entries/-/object.entries-1.1.0.tgz",
+      "integrity": "sha512-l+H6EQ8qzGRxbkHOd5I/aHRhHDKoQXQ8g0BYt4uSweQU1/J6dZUOyWh9a2Vky35YCKjzmgxOzta2hH6kf9HuXA==",
       "dev": true,
       "requires": {
-        "define-properties": "^1.1.2",
-        "es-abstract": "^1.6.1",
-        "function-bind": "^1.1.0",
-        "has": "^1.0.1"
+        "define-properties": "^1.1.3",
+        "es-abstract": "^1.12.0",
+        "function-bind": "^1.1.1",
+        "has": "^1.0.3"
       }
     },
     "object.getownpropertydescriptors": {
@@ -11884,9 +12070,9 @@
       "dev": true
     },
     "raf": {
-      "version": "3.4.0",
-      "resolved": "https://registry.npmjs.org/raf/-/raf-3.4.0.tgz",
-      "integrity": "sha512-pDP/NMRAXoTfrhCfyfSEwJAKLaxBU9eApMeBPB1TkDouZmvPerIClV8lTAd+uF8ZiTaVl69e1FCxQrAd/VTjGw==",
+      "version": "3.4.1",
+      "resolved": "https://registry.npmjs.org/raf/-/raf-3.4.1.tgz",
+      "integrity": "sha512-Sq4CW4QhwOHE8ucn6J34MqtZCeWFP2aQSmrlroYgqAV1PjStIhJXxYuTgUIfkEk7zTLjmIjLmU5q+fbD1NnOJA==",
       "dev": true,
       "requires": {
         "performance-now": "^2.1.0"
@@ -13828,14 +14014,41 @@
       }
     },
     "string.prototype.trim": {
-      "version": "1.1.2",
-      "resolved": "https://registry.npmjs.org/string.prototype.trim/-/string.prototype.trim-1.1.2.tgz",
-      "integrity": "sha1-0E3iyJ4Tf019IG8Ia17S+ua+jOo=",
+      "version": "1.2.0",
+      "resolved": "https://registry.npmjs.org/string.prototype.trim/-/string.prototype.trim-1.2.0.tgz",
+      "integrity": "sha512-9EIjYD/WdlvLpn987+ctkLf0FfvBefOCuiEr2henD8X+7jfwPnyvTdmW8OJhj5p+M0/96mBdynLWkxUr+rHlpg==",
       "dev": true,
       "requires": {
-        "define-properties": "^1.1.2",
-        "es-abstract": "^1.5.0",
-        "function-bind": "^1.0.2"
+        "define-properties": "^1.1.3",
+        "es-abstract": "^1.13.0",
+        "function-bind": "^1.1.1"
+      },
+      "dependencies": {
+        "es-abstract": {
+          "version": "1.13.0",
+          "resolved": "https://registry.npmjs.org/es-abstract/-/es-abstract-1.13.0.tgz",
+          "integrity": "sha512-vDZfg/ykNxQVwup/8E1BZhVzFfBxs9NqMzGcvIJrqg5k2/5Za2bWo40dK2J1pgLngZ7c+Shh8lwYtLGyrwPutg==",
+          "dev": true,
+          "requires": {
+            "es-to-primitive": "^1.2.0",
+            "function-bind": "^1.1.1",
+            "has": "^1.0.3",
+            "is-callable": "^1.1.4",
+            "is-regex": "^1.0.4",
+            "object-keys": "^1.0.12"
+          }
+        },
+        "es-to-primitive": {
+          "version": "1.2.0",
+          "resolved": "https://registry.npmjs.org/es-to-primitive/-/es-to-primitive-1.2.0.tgz",
+          "integrity": "sha512-qZryBOJjV//LaxLTV6UC//WewneB3LcXOL9NP++ozKVXsIIIpm/2c13UDiD9Jp2eThsecw9m3jPqDwTyobcdbg==",
+          "dev": true,
+          "requires": {
+            "is-callable": "^1.1.4",
+            "is-date-object": "^1.0.1",
+            "is-symbol": "^1.0.2"
+          }
+        }
       }
     },
     "string_decoder": {
@@ -14828,12 +15041,6 @@
         }
       }
     },
-    "underscore": {
-      "version": "1.4.4",
-      "resolved": "https://registry.npmjs.org/underscore/-/underscore-1.4.4.tgz",
-      "integrity": "sha1-YaajIBBiKvoHljvzJSA88SI51gQ=",
-      "dev": true
-    },
     "unescape": {
       "version": "0.2.0",
       "resolved": "https://registry.npmjs.org/unescape/-/unescape-0.2.0.tgz",
@@ -15238,6 +15445,12 @@
         "browser-process-hrtime": "^0.1.2"
       }
     },
+    "wait-for-expect": {
+      "version": "1.3.0",
+      "resolved": "https://registry.npmjs.org/wait-for-expect/-/wait-for-expect-1.3.0.tgz",
+      "integrity": "sha512-8fJU7jiA96HfGPt+P/UilelSAZfhMBJ52YhKzlmZQvKEZU2EcD1GQ0yqGB6liLdHjYtYAoGVigYwdxr5rktvzA==",
+      "dev": true
+    },
     "walker": {
       "version": "1.0.7",
       "resolved": "https://registry.npmjs.org/walker/-/walker-1.0.7.tgz",
diff --git a/package.json b/package.json
index 89d4456c914..cd84d867bd5 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@primer/components",
-  "version": "13.3.1",
+  "version": "13.4.0",
   "description": "Primer react components",
   "main": "dist/index.umd.js",
   "module": "dist/index.esm.js",
@@ -39,10 +39,11 @@
   "author": "GitHub, Inc.",
   "license": "MIT",
   "dependencies": {
-    "@primer/octicons-react": "9.0.0",
+    "@primer/octicons-react": "^9.0.0",
     "@reach/dialog": "0.2.9",
     "@styled-system/prop-types": "5.0.5",
     "@styled-system/theme-get": "5.0.5",
+    "@types/styled-system": "5.1.1",
     "babel-plugin-macros": "2.4.2",
     "classnames": "^2.2.5",
     "nanoid": "2.0.0",
@@ -60,11 +61,12 @@
     "@mdx-js/mdx": "0.15.0",
     "@mdx-js/tag": "0.15.0",
     "@svgr/webpack": "2.4.1",
+    "@testing-library/react": "8.0.6",
     "@zeit/next-mdx": "1.1.0",
     "babel-core": "7.0.0-bridge.0",
     "babel-plugin-add-react-displayname": "0.0.5",
     "babel-plugin-styled-components": "1.10.0",
-    "enzyme": "3.5.1",
+    "enzyme": "3.10.0",
     "enzyme-adapter-react-16": "1.5.0",
     "eslint": "4.19.1",
     "eslint-plugin-github": "1.0.0",
diff --git a/pages/components/docs/TabNav.md b/pages/components/docs/TabNav.md
new file mode 100644
index 00000000000..87ed900d2ed
--- /dev/null
+++ b/pages/components/docs/TabNav.md
@@ -0,0 +1,46 @@
+# TabNav
+
+Use the TabNav component to style navigation with a tab-based selected state, typically used for navigation placed at the top of the page.
+
+To use TabNav with [react-router](https://github.com/ReactTraining/react-router) or
+[react-router-dom](https://www.npmjs.com/package/react-router-dom), pass
+`as={NavLink}` and omit the `selected` prop.
+This ensures that the NavLink gets `activeClassName='selected'`
+
+**Attention:** Make sure to properly label your `TabNav` with an `aria-label` to provide context about the type of navigation contained in `TabNav`.
+
+## Default example
+
+```.jsx
+<ExampleHeading>
+  Using <Text fontFamily="mono">{'<TabNav.Link>'}</Text>
+</ExampleHeading>
+<TabNav aria-label="Main">
+  <TabNav.Link href="#home" selected>
+    Home
+  </TabNav.Link>
+  <TabNav.Link href="#documentation">Documentation</TabNav.Link>
+  <TabNav.Link href="#support">Support</TabNav.Link>
+</TabNav>
+```
+
+## System props
+
+TabNav and TabNav.Link components get `COMMON` system props. Read our [System Props](/components/docs/system-props) doc page for a full list of available props.
+
+## Component props
+
+### TabNav
+
+| Prop name  | Type   | Description                                                    |
+| :--------- | :----- | :------------------------------------------------------------- |
+| aria-label | String | Used to set the `aria-label` on the top level `<nav>` element. |
+
+### TabNav.Link
+
+| Prop name | Type    | Description                                      |
+| :-------- | :------ | :----------------------------------------------- |
+| as        | String  | sets the HTML tag for the component              |
+| selected  | Boolean | Used to style the link as selected or unselected |
+
+export const meta = {displayName: 'TabNav'}
diff --git a/pages/components/docs/core-concepts b/pages/components/docs/core-concepts.md
similarity index 97%
rename from pages/components/docs/core-concepts
rename to pages/components/docs/core-concepts.md
index 336117cbfe5..5f0479b5d6c 100644
--- a/pages/components/docs/core-concepts
+++ b/pages/components/docs/core-concepts.md
@@ -51,7 +51,7 @@ We categorize our components into 3 general types. Building block components, pa
  For example, say you are using a `Button` component, and you really need to apply `Flex` styles to it. You can compose `Flex` and `Button` like so:
 
  ```.jsx
- <Flex as={Button}/>
+ <Flex as={Button} href='https://github.com'>Hello</Flex>
  ```
 
  This will allow you to use all of the `Button` props _and_ all of the `Flex` props without having to wrap your `Button` component in another `Flex` component.
@@ -62,6 +62,6 @@ For these reasons, **we recommend only using the `as` prop when you cannot achie
 
 ```.jsx
 <Flex>
-  <Button>Hi</Button>
+  <Button href='https://github.com'>Hi</Button>
 </Flex>
 ```
diff --git a/pages/components/docs/index.js b/pages/components/docs/index.js
index e01f0bb282f..432bf066174 100644
--- a/pages/components/docs/index.js
+++ b/pages/components/docs/index.js
@@ -20,6 +20,7 @@ export {meta as PointerBox} from './PointerBox.md'
 export {meta as Position} from './Position.md'
 export {meta as StateLabel} from './StateLabel.md'
 export {meta as StyledOcticon} from './StyledOcticon.md'
+export {meta as TabNav} from './TabNav.md'
 export {meta as TextInput} from './TextInput.md'
 export {meta as Text} from './Text.md'
 export {meta as Tooltip} from './Tooltip.md'
diff --git a/pages/doc-components/SideNav.js b/pages/doc-components/SideNav.js
index 6273bd7af33..a745758e07d 100644
--- a/pages/doc-components/SideNav.js
+++ b/pages/doc-components/SideNav.js
@@ -68,6 +68,7 @@ const SideNav = ({router}) => (
               color="gray.9"
               href="/components/docs/primer-theme"
               m={0}
+              mb={4}
               fontWeight={router.pathname === '/components/docs/primer-theme' ? 'bold' : null}
             >
               Primer Theme
diff --git a/src/TabNav.js b/src/TabNav.js
new file mode 100644
index 00000000000..ddb64bf1f04
--- /dev/null
+++ b/src/TabNav.js
@@ -0,0 +1,79 @@
+import React from 'react'
+import PropTypes from 'prop-types'
+import classnames from 'classnames'
+import styled from 'styled-components'
+import {COMMON, get} from './constants'
+import theme from './theme'
+
+const ITEM_CLASS = 'TabNav-item'
+const SELECTED_CLASS = 'selected'
+
+function TabNavBase({actions, className, align, children, full, label, ...rest}) {
+  const classes = classnames(className, 'TabNav')
+  return (
+    <nav className={classes} aria-label={label} {...rest}>
+      <div className="TabNav-body">{children}</div>
+    </nav>
+  )
+}
+
+const TabNav = styled(TabNavBase)`
+  display: flex;
+  border-bottom: 1px solid ${get('colors.gray.3')};
+
+  .TabNav-body {
+    display: flex;
+    margin-bottom: -1px;
+  }
+
+  ${COMMON};
+`
+
+TabNav.Link = styled.a.attrs(props => ({
+  activeClassName: typeof props.to === 'string' ? 'selected' : '',
+  className: classnames(ITEM_CLASS, props.selected && SELECTED_CLASS, props.className)
+}))`
+  padding: 8px 12px;
+  font-size: ${get('fontSizes.1')}px;
+  line-height: 20px;
+  color: ${get('colors.gray.6')};
+  text-decoration: none;
+  background-color: transparent;
+  border: 1px solid transparent;
+  border-bottom: 0;
+
+  &:hover,
+  &:focus {
+    color: ${get('colors.gray.9')};
+    text-decoration: none;
+  }
+
+  &.selected {
+    color: ${get('colors.gray.9')};
+    border-color: ${get('colors.gray.3')};
+    border-radius: 3px 3px 0 0;
+    background-color: ${get('colors.white')};
+  }
+`
+
+TabNav.defaultProps = {
+  theme
+}
+
+TabNav.propTypes = {
+  children: PropTypes.node,
+  theme: PropTypes.object,
+  ...COMMON.propTypes
+}
+
+TabNav.Link.defaultProps = {
+  theme
+}
+
+TabNav.Link.propTypes = {
+  as: PropTypes.oneOfType([PropTypes.string, PropTypes.func]),
+  selected: PropTypes.bool,
+  ...COMMON.propTypes
+}
+
+export default TabNav
diff --git a/src/__tests__/TabNav.js b/src/__tests__/TabNav.js
new file mode 100644
index 00000000000..a79be33b942
--- /dev/null
+++ b/src/__tests__/TabNav.js
@@ -0,0 +1,34 @@
+import React from 'react'
+import TabNav from '../TabNav'
+import {mount, render, rendersClass} from '../utils/testing'
+import {COMMON} from '../constants'
+
+describe('TabNav', () => {
+  it('implements system props', () => {
+    expect(TabNav).toImplementSystemProps(COMMON)
+  })
+
+  it('has default theme', () => {
+    expect(TabNav).toSetDefaultTheme()
+  })
+
+  it('renders a <nav>', () => {
+    expect(render(<TabNav />).type).toEqual('nav')
+  })
+
+  it('adds the TabNav class', () => {
+    expect(rendersClass(<TabNav />, 'TabNav')).toEqual(true)
+  })
+
+  it('sets aria-label appropriately', () => {
+    expect(render(<TabNav aria-label="foo" />).props['aria-label']).toEqual('foo')
+  })
+
+  it('wraps its children in an "TabNav-body" div', () => {
+    const children = <b>children</b>
+    const wrapper = mount(<TabNav>{children}</TabNav>)
+    const body = wrapper.find('.TabNav-body')
+    expect(body.exists()).toEqual(true)
+    expect(body.childAt(0).type()).toEqual('b')
+  })
+})
diff --git a/src/index.js b/src/index.js
index feab2981170..735d0de3f12 100644
--- a/src/index.js
+++ b/src/index.js
@@ -33,6 +33,7 @@ export {default as Link} from './Link'
 export {default as PointerBox} from './PointerBox'
 export {default as StateLabel} from './StateLabel'
 export {default as StyledOcticon} from './StyledOcticon'
+export {default as TabNav} from './TabNav'
 export {default as TextInput} from './TextInput'
 export {default as Text} from './Text'
 export {default as Tooltip} from './Tooltip'