diff --git a/README.md b/README.md
index 07011d3..76c63c0 100644
--- a/README.md
+++ b/README.md
@@ -165,7 +165,7 @@ person.mergedValues({"CO": "Boulder"});
 person.mergedValues(); // {"CO": "Boulder", "KS": "Wichita"}
 ```
 
-### `.filter`
+### `.filter(filterFunction)`
 
 ``` javascript
 class Person extends Component {
@@ -189,6 +189,27 @@ person.favoriteNumber("1");
 person.favoriteNumber(); // 1
 ```
 
+### `.then(callback)`
+
+Call a synchronous callback each time a new value is set on the property
+
+``` javascript
+class Person extends Component {
+  initialize() {
+    this.properties("favoriteNumber").then(this.doSomething);
+  }
+
+  doSomething(value) {
+    // No returns. Just a simple synchronous callback.
+  }
+}
+
+const person = new Person();
+
+person.favoriteNumber("1");
+person.favoriteNumber(); // 1
+```
+
 ## `.link(linkName, linkConstructor)`
 
 A link creates a method which returns a new instance of the provided `linkConstructor`.
diff --git a/package.json b/package.json
index bc23511..50afe01 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "mrt",
-  "version": "0.4.3",
+  "version": "0.4.4",
   "description": "Helps build expressive chained interfaces.",
   "main": "index.js",
   "scripts": {