diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Revision history for database-id-class
 
+## 0.1.0.1
+
+* Add readme
+
 ## 0.1.0.0
 
 * Initial release. Contains HasId class and associated instances.
diff --git a/README.md b/README.md
new file mode 100644
--- /dev/null
+++ b/README.md
@@ -0,0 +1,14 @@
+database-id-class
+-----------------
+
+This package defines a (parametric) data type `Id a` used to refer to the primary key of values of type `a` in a database.
+
+    newtype Id a = Id { unId :: IdData a }
+
+Here, `IdData` is a type family associated with the `HasId` class:
+
+    class HasId a where
+      type IdData a :: *
+      type IdData a = Int64
+
+It defaults to `Int64` because that tends to be the type you want for tables with an autoincrement primary key.
diff --git a/database-id-class.cabal b/database-id-class.cabal
--- a/database-id-class.cabal
+++ b/database-id-class.cabal
@@ -1,6 +1,6 @@
 cabal-version:       >=1.10
 name:                database-id-class
-version:             0.1.0.0
+version:             0.1.0.1
 synopsis:            Class for types with a database id
 description:         Class for types with a database id
 -- bug-reports:
@@ -12,6 +12,7 @@
 category:            Database
 build-type:          Simple
 extra-source-files:  CHANGELOG.md
+                     README.md
 
 library
   exposed-modules: Database.Id.Class