diff --git a/README.md b/README.md
index ecf9c4e..a5afeca 100644
--- a/README.md
+++ b/README.md
@@ -16,3 +16,49 @@
 * [godoc.org/golang.org/x/oauth2/google](http://godoc.org/golang.org/x/oauth2/google)
 
 
+## App Engine
+
+In change 96e89be (March 2015) we removed the `oauth2.Context2` type in favor
+of the [`context.Context`](https://golang.org/x/net/context#Context) type from
+the `golang.org/x/net/context` package
+
+This means its no longer possible to use the "Classic App Engine"
+`appengine.Context` type with the `oauth2` package. (You're using
+Classic App Engine if you import the package `"appengine"`.)
+
+To work around this, you may use the new `"google.golang.org/appengine"`
+package. This package has almost the same API as the `"appengine"` package,
+but it can be fetched with `go get` and used on "Managed VMs" and well as
+Classic App Engine.
+
+See the [new `appengine` package's readme](https://github.com/golang/appengine#updating-a-go-app-engine-app)
+for information on updating your app.
+
+If you don't want to update your entire app to use the new App Engine packages,
+you may use both sets of packages in parallel, using only the new packages
+with the `oauth2` package.
+
+	import (
+		"golang.org/x/net/context"
+		"golang.org/x/oauth2"
+		"golang.org/x/oauth2/google"
+		newappengine "google.golang.org/appengine"
+		newurlftech "google.golang.org/urlfetch"
+
+		"appengine"
+	)
+
+	func handler(w http.ResponseWriter, r *http.Request) {
+		var c appengine.Context = appengine.NewContext(r)
+		c.Infof("Logging a message with the old package")
+
+		var ctx context.Context = newappengine.NewContext(r)
+		client := &http.Client{
+			Transport: &oauth2.Transport{
+				Source: google.AppEngineTokenSource(ctx, "scope"),
+				Base:   &newurlfetch.Transport{Context: ctx},
+			},
+		}
+		client.Get("...")
+	}
+