diff --git a/packages/interactive_media_ads/CHANGELOG.md b/packages/interactive_media_ads/CHANGELOG.md
index 33c46a6965d2..139996489e08 100644
--- a/packages/interactive_media_ads/CHANGELOG.md
+++ b/packages/interactive_media_ads/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.1.2+3
+
+* Adds a contribution guide. See `CONTRIBUTING.md`.
+
 ## 0.1.2+2
 
 * Removes dependency on org.jetbrains.kotlin:kotlin-bom.
diff --git a/packages/interactive_media_ads/CONTRIBUTING.md b/packages/interactive_media_ads/CONTRIBUTING.md
new file mode 100644
index 000000000000..7ea6e025646a
--- /dev/null
+++ b/packages/interactive_media_ads/CONTRIBUTING.md
@@ -0,0 +1,239 @@
+# Contributing to `interactive_media_ads`
+
+Please start by taking a look at the general guide to contributing to the `flutter/packages` repo:
+https://github.com/flutter/packages/blob/main/CONTRIBUTING.md
+
+## Package Structure
+
+The structure of this plugin is similar to a [federated plugin](https://docs.flutter.dev/packages-and-plugins/developing-packages#federated-plugins),
+except the code for each package (platform interface, platform implementations, and app-facing
+interface) are maintained in this single plugin. The sections below will provide an overview of how
+this plugin implements each portion.
+
+If you are familiar with [changing federated plugin](https://github.com/flutter/flutter/blob/master/docs/ecosystem/contributing/README.md#changing-federated-plugins)
+in the `flutter/packages` repo, the process is similar except that all changes are made in this
+plugin. Therefore, it is not necessary to run the script that makes dependencies path based.
+
+### Quick Overview
+
+This plugin uses the native [IMA SDKs] for Android and iOS. The API for the SDK of both platforms
+are relatively similar, so this plugin attempts to maintain an interface that is similar to the
+native SDKs.
+
+The app-facing interface uses delegation to interact with the underlying platform implementations.
+Therefore, the platform interface is similar to the app-facing interface with the differences being
+explained in the sections below. Many app-facing interface classes will contain a `platform` field
+that is used to forward handling to the platform implementation:
+
+```dart
+// App-facing class used by apps
+class AdsLoader {
+  AdsLoader.fromPlatform(this.platform);
+  
+  final PlatformAdsLoader platform;
+  
+  Future<void> requestAds(AdsRequest request) {
+    return platform.requestAds(request);
+  }
+}
+
+// Platform interface class implemented by each platform
+abstract base class PlatformAdsLoader {
+  Future<void> requestAds(AdsRequest request);
+}
+```
+
+The `platform` variable should also be used to provide access to platform specific methods or
+platform specific creation parameters:
+
+```dart
+final AdsLoader loader = AdsLoader();
+(loader.platform as AndroidAdsLoader).callAndroidSpecificMethod();
+```
+
+The other classes/enums included in the app-facing interface are typically exported from the
+platform interface. A data class being a good example of a class that is exported.
+
+### Platform Interface
+
+Code location: `lib/src/platform_interface/`.
+
+This declares an interface that each platform must implement to be supported by the app-facing
+interface.
+
+The design of the platform interface should prioritize:
+* Minimizing the chances of needing a breaking change when adding a new feature.
+* Allowing platform implementations to easily add platform specific features.
+* Being straight-forward to write unit tests.
+
+Each platform creates a subclass of the central [InteractiveMediaAdsPlatform](lib/src/platform_interface/interactive_media_ads_platform.dart)
+class. A platform implementation is set by setting `InteractiveMediaAdsPlatform.instance` to an
+instance of a platform implementation of `InteractiveMediaAdsPlatform`.
+
+### Platform Interface Class Types
+
+Below are some of the types of classes in the interface.
+
+#### Delegate Platform Class
+
+These are classes where the app-facing interface needs to delegate handling to the platform
+implementation. These classes are typically prefixed with `Platform`.
+
+If the corresponding app-facing class can be instantiated by the app (e.g. [AdsLoader]),
+the `InteractiveMediaAdsPlatform.instance` field should be used in a factory to instantiate the
+correct platform implementation. See [PlatformAdsLoader] as an example. This class should should
+also take a creation params class as the only constructor parameter. 
+
+If the corresponding app-facing class can't be instantiated by the app (e.g. `AdsManager`), the
+class should only have a single protected constructor. See [PlatformAdsManager].
+
+If the corresponding app-facing class needs to be a `Widget` (e.g. [AdDisplayContainer]), this
+should follow the same pattern as being instantiable by the app except it should contain a single
+method: `Widget build(BuildContext)`. See [PlatformAdDisplayContainer].
+
+**Note**
+
+Every method should contain no more than one parameter. This allows the platform interface and
+platform implementations to add new features without requiring a breaking change.
+
+#### Data Classes
+
+These classes contain only fields and no methods. Each data class should be made `@immutable`.
+
+### Platform Implementations
+
+Code location:
+* Android: `lib/src/android/`
+* iOS: `lib/src/ios/`
+
+The platform implementations create a subclass of `InteractiveMediaAdsPlatform` and implement the 
+platform classes that are returned by this.
+
+#### SDK Wrappers
+
+The platform implementations use Dart wrappers of their native SDKs. The SDKs are wrapped using
+using the `pigeon` package. However, the code that handles generating the wrappers are still in the
+process of review, so this plugin must use a git dependency in the pubspec.
+
+The wrappers for the SDK of each platform can be updated and modified by changing the pigeon files:
+
+* Android: `pigeons/interactive_media_ads_android.dart`
+* iOS: `pigeons/interactive_media_ads_ios.dart`
+
+The generated files are located:
+* Android:
+  * `lib/src/android/interactive_media_ads.g.dart`
+  * `android/src/main/kotlin/dev/flutter/packages/interactive_media_ads/InteractiveMediaAdsLibrary.g.kt`
+* iOS
+  * `lib/src/ios/interactive_media_ads.g.dart`
+  *  `ios/interactive_media_ads/Sources/interactive_media_ads/InteractiveMediaAdsLibrary.g.swift`
+
+To update a wrapper for a platform, follow the steps:
+
+##### 1. Ensure the project has been built at least once
+
+* Android: Run `flutter build apk --debug` in `example/`.
+* iOS: Run `flutter build ios --simulator` in `example/`
+
+##### 2. Add the correct `pigeon` package to `dev_dependencies` in the `pubspec.yaml` and run `pub upgrade`
+
+Android:
+
+```yaml
+pigeon:
+    git:
+      url: git@github.com:bparrishMines/packages.git
+      ref: pigeon_kotlin_split
+      path: packages/pigeon
+```
+
+iOS:
+
+```yaml
+pigeon:
+    git:
+      url: git@github.com:bparrishMines/packages.git
+      ref: pigeon_wrapper_swift
+      path: packages/pigeon
+```
+
+##### 3. Uncomment the multiline comments in the pigeon file
+
+* Android: `pigeons/interactive_media_ads_android.dart`
+* iOS: `pigeons/interactive_media_ads_ios.dart`
+
+##### 4. Make changes that match the native SDK
+
+* [Android SDK]
+* [iOS SDK]
+
+##### 5. Run the code generator from the terminal
+
+* Android: `dart run pigeon --input pigeons/interactive_media_ads_android.dart`
+* iOS: `dart run pigeon --input pigeons/interactive_media_ads_ios.dart`
+
+##### 6. Update the generated APIs in native code
+
+Running the `flutter build` step from step 1 again should provide build errors and indicate what
+needs to be done. Alternatively, it can be easier to update native code with the platform's specific
+IDE:
+
+* Android: Open `example/android/` in a separate Android Studio project.
+* iOS: Open `example/ios/` in Xcode.
+
+##### 7. Write API tests
+
+Assuming a non-static method or constructor was added to the native wrapper, a native test will need
+to be added.
+
+* Android native tests location: `android/src/test/kotlin/dev/flutter/packages/interactive_media_ads/`
+* iOS native tests location `example/ios/RunnerTests/`
+
+#### Dart Unit Testing
+
+Tests for the platform implementations use [mockito] to generate mock objects of the native Dart
+wrappers. To generate the mock objects in `test/`, run
+`dart run build_runner build --delete-conflicting-outputs`.
+
+### App-facing Interface
+
+Code location: `lib/src/`
+
+The app-facing interface shares the same structure as the platform interface and uses delegation
+to forward handling to the platform implementation. Note a few differences from the platform
+interface:
+
+* Constructors and methods can contain more than one parameter.
+* Platform classes can be instantiated with a platform implementation or creation params of
+  the corresponding platform interface class. See `AdsLoader.fromPlatform` and
+  `AdsLoader.fromPlatformCreationParams`.
+
+## Recommended Process for Adding a New Feature
+
+### 1. Create a new feature request issue in the `flutter/flutter` repo.
+
+See https://github.com/flutter/flutter/issues/new?assignees=&labels=&projects=&template=3_feature_request.yml
+
+### 2. In that issue add the specific native classes/methods that this feature requires for each platform:
+
+* [Android SDK]
+* [iOS SDK]
+
+Add a note if this feature only exist for a single platform. 
+
+### 3. Add a design where the feature can be added to the platform interface and app-facing interface.
+
+If this is only supported on a single platform, add where it can be added in the platform 
+implementation.
+
+### 4. Work can be started on the feature request or you can wait for feedback from a Flutter contributor.
+
+[IMA SDKs]: https://developers.google.com/interactive-media-ads
+[AdsLoader]: lib/src/ads_loader.dart
+[AdDisplayContainer]: lib/src/ad_display_container.dart
+[PlatformAdsLoader]: lib/src/platform_interface/platform_ads_loader.dart
+[PlatformAdsManager]: lib/src/platform_interface/platform_ads_manager.dart
+[PlatformAdDisplayContainer]: lib/src/platform_interface/platform_ad_display_container.dart
+[Android SDK]: https://developers.google.com/interactive-media-ads/docs/sdks/android/client-side/api/reference/com/google/ads/interactivemedia/v3/api/package-summary
+[iOS SDK]: https://developers.google.com/interactive-media-ads/docs/sdks/ios/client-side/reference/Classes
+[mockito]: https://pub.dev/packages/mockito
diff --git a/packages/interactive_media_ads/README.md b/packages/interactive_media_ads/README.md
index 94d996a2f950..01324117f222 100644
--- a/packages/interactive_media_ads/README.md
+++ b/packages/interactive_media_ads/README.md
@@ -15,9 +15,9 @@ a separate video player positioned on top of the app's content video player.
 
 **NOTE:**
 * The initial release for this package supports linear pre-roll video ads on iOS and Android
-* platforms.
+  platforms.
 * Companion ads, Background Audio ads and Google Dynamic Ad Insertion methods are currently not
-* supported.
+  supported.
 
 ## IMA client-side overview
 
@@ -272,6 +272,10 @@ void dispose() {
 That's it! You're now requesting and displaying ads with the IMA SDK. To learn about additional SDK
 features, see the [API reference](https://pub.dev/documentation/interactive_media_ads/latest/).
 
+## Contributing
+
+For information on contributing to this plugin, see [`CONTRIBUTING.md`](CONTRIBUTING.md).
+
 [1]: https://developers.google.com/interactive-media-ads
 [2]: https://www.iab.com/guidelines/vast/
 [3]: https://pub.dev/documentation/interactive_media_ads/latest/interactive_media_ads/AdDisplayContainer-class.html
diff --git a/packages/interactive_media_ads/android/src/main/kotlin/dev/flutter/packages/interactive_media_ads/AdsRequestProxyApi.kt b/packages/interactive_media_ads/android/src/main/kotlin/dev/flutter/packages/interactive_media_ads/AdsRequestProxyApi.kt
index f9d27e3f071b..e30a7d1dd5cf 100644
--- a/packages/interactive_media_ads/android/src/main/kotlin/dev/flutter/packages/interactive_media_ads/AdsRequestProxyApi.kt
+++ b/packages/interactive_media_ads/android/src/main/kotlin/dev/flutter/packages/interactive_media_ads/AdsRequestProxyApi.kt
@@ -21,7 +21,7 @@ class AdsRequestProxyApi(override val pigeonRegistrar: ProxyApiRegistrar) :
      *
      * This must match the version in pubspec.yaml.
      */
-    const val pluginVersion = "0.1.2+2"
+    const val pluginVersion = "0.1.2+3"
   }
 
   override fun setAdTagUrl(pigeon_instance: AdsRequest, adTagUrl: String) {
diff --git a/packages/interactive_media_ads/ios/interactive_media_ads/Sources/interactive_media_ads/AdsRequestProxyAPIDelegate.swift b/packages/interactive_media_ads/ios/interactive_media_ads/Sources/interactive_media_ads/AdsRequestProxyAPIDelegate.swift
index 132d5055c3fe..a09743229803 100644
--- a/packages/interactive_media_ads/ios/interactive_media_ads/Sources/interactive_media_ads/AdsRequestProxyAPIDelegate.swift
+++ b/packages/interactive_media_ads/ios/interactive_media_ads/Sources/interactive_media_ads/AdsRequestProxyAPIDelegate.swift
@@ -13,7 +13,7 @@ class AdsRequestProxyAPIDelegate: PigeonApiDelegateIMAAdsRequest {
   /// The current version of the `interactive_media_ads` plugin.
   ///
   /// This must match the version in pubspec.yaml.
-  static let pluginVersion = "0.1.2+2"
+  static let pluginVersion = "0.1.2+3"
 
   func pigeonDefaultConstructor(
     pigeonApi: PigeonApiIMAAdsRequest, adTagUrl: String, adDisplayContainer: IMAAdDisplayContainer,
diff --git a/packages/interactive_media_ads/pubspec.yaml b/packages/interactive_media_ads/pubspec.yaml
index a6a59d96cdaa..37b8a923e2bd 100644
--- a/packages/interactive_media_ads/pubspec.yaml
+++ b/packages/interactive_media_ads/pubspec.yaml
@@ -2,7 +2,7 @@ name: interactive_media_ads
 description: A Flutter plugin for using the Interactive Media Ads SDKs on Android and iOS.
 repository: https://github.com/flutter/packages/tree/main/packages/interactive_media_ads
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+interactive_media_ads%22
-version: 0.1.2+2 # This must match the version in
+version: 0.1.2+3 # This must match the version in
   # `android/src/main/kotlin/dev/flutter/packages/interactive_media_ads/AdsRequestProxyApi.kt` and
   # `ios/interactive_media_ads/Sources/interactive_media_ads/AdsRequestProxyAPIDelegate.swift`