diff --git a/examples/build.sbt b/examples/build.sbt
index fc34c68..3883432 100644
--- a/examples/build.sbt
+++ b/examples/build.sbt
@@ -75,6 +75,12 @@ lazy val extension = project.in(file("extension"))
       val background = Background(
         scripts = Chrome.defaultScripts
       )
+      override val contentScripts = List(
+        ContentScript(
+          matches = Set("https://www.example.org/*"),
+          js = Chrome.defaultScripts
+        )
+      )
       val name = Keys.name.value
       val version = Keys.version.value
       override val icons = Chrome.icons(
diff --git a/examples/extension/src/main/scala/Main.scala b/examples/extension/src/main/scala/Main.scala
index 2701ec2..13e8c11 100644
--- a/examples/extension/src/main/scala/Main.scala
+++ b/examples/extension/src/main/scala/Main.scala
@@ -1,3 +1,4 @@
+import scala.scalajs.js
 import scala.scalajs.js.JSApp
 
 object Main extends JSApp {
diff --git a/sbt-plugin/src/main/scala/net/lullabyte/JsonCodecs.scala b/sbt-plugin/src/main/scala/net/lullabyte/JsonCodecs.scala
index d73c0ab..830aa4f 100644
--- a/sbt-plugin/src/main/scala/net/lullabyte/JsonCodecs.scala
+++ b/sbt-plugin/src/main/scala/net/lullabyte/JsonCodecs.scala
@@ -39,6 +39,26 @@ object JsonCodecs {
       )
   }
 
+  implicit val runAtEncoder = Encoder.instance[chrome.RunAt] {
+    case RunAt.DocumentStart => Json.fromString("document_start")
+    case RunAt.DocumentEnd => Json.fromString("document_end")
+    case RunAt.DocumentIdle => Json.fromString("document_idle")
+  }
+
+  implicit val contentScriptEncoder = Encoder.instance[chrome.ContentScript] { cs =>
+    Json.obj(
+      ("matches", Json.fromValues(cs.matches.map(Json.fromString))),
+      ("exclude_matches", omitIfEmpty(cs.excludeMatches)(Json.fromString)),
+      ("match_about_blank", cs.matchAboutBlank.asJson),
+      ("css", omitIfEmpty(cs.css)(Json.fromString)),
+      ("js", omitIfEmpty(cs.js)(Json.fromString)),
+      ("run_at", cs.runAt.asJson),
+      ("all_frames", cs.allFrames.asJson),
+      ("include_globs", omitIfEmpty(cs.includeGlobs)(Json.fromString)),
+      ("exclude_globs", omitIfEmpty(cs.css)(Json.fromString))
+    )
+  }
+
   implicit val omniboxEncoder = Encoder.instance[chrome.Omnibox] { omnibox =>
     Json.obj(
       ("keyword", Json.fromString(omnibox.keyword))
@@ -187,6 +207,7 @@ object JsonCodecs {
     val commonValues = manifest2json(manifest)
     val extValues = Seq(
       ("background", manifest.background.asJson),
+      ("content_scripts", omitIfEmpty(manifest.contentScripts)(_.asJson)),
       ("omnibox", manifest.omnibox.asJson),
       ("options_ui", manifest.optionsUI.asJson),
       ("browser_action", manifest.browserAction.asJson),
diff --git a/shared/src/main/scala/chrome/Manifest.scala b/shared/src/main/scala/chrome/Manifest.scala
index 18d86a0..ad9b367 100644
--- a/shared/src/main/scala/chrome/Manifest.scala
+++ b/shared/src/main/scala/chrome/Manifest.scala
@@ -28,6 +28,24 @@ sealed trait Manifest {
 
 case class Background(scripts: List[String])
 case class App(background: Background)
+case class ContentScript(
+    matches: Set[String],
+    excludeMatches: Set[String] = Set.empty,
+    matchAboutBlank: Option[Boolean] = None,
+    css: List[String] = List.empty,
+    js: List[String] = List.empty,
+    runAt: Option[RunAt] = None,
+    allFrames: Option[Boolean] = None,
+    includeGlobs: Set[String] = Set.empty,
+    excludeGlobs: Set[String] = Set.empty
+)
+
+sealed trait RunAt
+object RunAt {
+  case object DocumentStart extends RunAt
+  case object DocumentEnd extends RunAt
+  case object DocumentIdle extends RunAt
+}
 
 case class BrowserAction(
     icon: Map[Int, String] = Map.empty,
@@ -98,6 +116,7 @@ trait AppManifest extends chrome.Manifest {
 
 trait ExtensionManifest extends chrome.Manifest {
   val background: Background
+  val contentScripts: List[ContentScript] = List.empty
   val browserAction: Option[BrowserAction] = None
   val omnibox: Option[Omnibox] = None
   val optionsUI: Option[OptionsUI] = None