diff --git a/core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/OfflineFirstUserDataRepository.kt b/core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/OfflineFirstUserDataRepository.kt
index 334209538..f10046f73 100644
--- a/core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/OfflineFirstUserDataRepository.kt
+++ b/core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/OfflineFirstUserDataRepository.kt
@@ -50,6 +50,9 @@ class OfflineFirstUserDataRepository @Inject constructor(
         )
     }
 
+    override suspend fun updateNewsResourceViewed(newsResourceId: String, viewed: Boolean) =
+        niaPreferencesDataSource.toggleNewsResourceViewed(newsResourceId, viewed)
+
     override suspend fun setThemeBrand(themeBrand: ThemeBrand) {
         niaPreferencesDataSource.setThemeBrand(themeBrand)
         analyticsHelper.logThemeChanged(themeBrand.name)
diff --git a/core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/UserDataRepository.kt b/core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/UserDataRepository.kt
index ea093852f..2ce84a963 100644
--- a/core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/UserDataRepository.kt
+++ b/core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/UserDataRepository.kt
@@ -43,6 +43,11 @@ interface UserDataRepository {
      */
     suspend fun updateNewsResourceBookmark(newsResourceId: String, bookmarked: Boolean)
 
+    /**
+     * Updates the viewed status for a news resource
+     */
+    suspend fun updateNewsResourceViewed(newsResourceId: String, viewed: Boolean)
+
     /**
      * Sets the desired theme brand.
      */
diff --git a/core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/fake/FakeUserDataRepository.kt b/core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/fake/FakeUserDataRepository.kt
index af206e5c7..8b8a1f7f8 100644
--- a/core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/fake/FakeUserDataRepository.kt
+++ b/core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/fake/FakeUserDataRepository.kt
@@ -47,6 +47,9 @@ class FakeUserDataRepository @Inject constructor(
         niaPreferencesDataSource.toggleNewsResourceBookmark(newsResourceId, bookmarked)
     }
 
+    override suspend fun updateNewsResourceViewed(newsResourceId: String, viewed: Boolean) =
+        niaPreferencesDataSource.toggleNewsResourceViewed(newsResourceId, viewed)
+
     override suspend fun setThemeBrand(themeBrand: ThemeBrand) {
         niaPreferencesDataSource.setThemeBrand(themeBrand)
     }
diff --git a/core/data/src/test/java/com/google/samples/apps/nowinandroid/core/data/repository/OfflineFirstUserDataRepositoryTest.kt b/core/data/src/test/java/com/google/samples/apps/nowinandroid/core/data/repository/OfflineFirstUserDataRepositoryTest.kt
index daf1a6564..994ae71b5 100644
--- a/core/data/src/test/java/com/google/samples/apps/nowinandroid/core/data/repository/OfflineFirstUserDataRepositoryTest.kt
+++ b/core/data/src/test/java/com/google/samples/apps/nowinandroid/core/data/repository/OfflineFirstUserDataRepositoryTest.kt
@@ -66,6 +66,7 @@ class OfflineFirstUserDataRepositoryTest {
             assertEquals(
                 UserData(
                     bookmarkedNewsResources = emptySet(),
+                    viewedNewsResources = emptySet(),
                     followedTopics = emptySet(),
                     themeBrand = ThemeBrand.DEFAULT,
                     darkThemeConfig = DarkThemeConfig.FOLLOW_SYSTEM,
@@ -160,6 +161,37 @@ class OfflineFirstUserDataRepositoryTest {
             )
         }
 
+    @Test
+    fun offlineFirstUserDataRepository_update_viewed_news_resources_delegates_to_nia_preferences() =
+        runTest {
+            subject.updateNewsResourceViewed(newsResourceId = "0", viewed = true)
+
+            assertEquals(
+                setOf("0"),
+                subject.userData
+                    .map { it.viewedNewsResources }
+                    .first(),
+            )
+
+            subject.updateNewsResourceViewed(newsResourceId = "1", viewed = true)
+
+            assertEquals(
+                setOf("0", "1"),
+                subject.userData
+                    .map { it.viewedNewsResources }
+                    .first(),
+            )
+
+            assertEquals(
+                niaPreferencesDataSource.userData
+                    .map { it.viewedNewsResources }
+                    .first(),
+                subject.userData
+                    .map { it.viewedNewsResources }
+                    .first(),
+            )
+        }
+
     @Test
     fun offlineFirstUserDataRepository_set_theme_brand_delegates_to_nia_preferences() =
         testScope.runTest {
diff --git a/core/datastore/src/main/java/com/google/samples/apps/nowinandroid/core/datastore/NiaPreferencesDataSource.kt b/core/datastore/src/main/java/com/google/samples/apps/nowinandroid/core/datastore/NiaPreferencesDataSource.kt
index f5751193a..91f8a3df2 100644
--- a/core/datastore/src/main/java/com/google/samples/apps/nowinandroid/core/datastore/NiaPreferencesDataSource.kt
+++ b/core/datastore/src/main/java/com/google/samples/apps/nowinandroid/core/datastore/NiaPreferencesDataSource.kt
@@ -33,6 +33,7 @@ class NiaPreferencesDataSource @Inject constructor(
         .map {
             UserData(
                 bookmarkedNewsResources = it.bookmarkedNewsResourceIdsMap.keys,
+                viewedNewsResources = it.viewedNewsResourceIdsMap.keys,
                 followedTopics = it.followedTopicIdsMap.keys,
                 themeBrand = when (it.themeBrand) {
                     null,
@@ -137,6 +138,18 @@ class NiaPreferencesDataSource @Inject constructor(
         }
     }
 
+    suspend fun toggleNewsResourceViewed(newsResourceId: String, viewed: Boolean) {
+        userPreferences.updateData {
+            it.copy {
+                if (viewed) {
+                    viewedNewsResourceIds.put(newsResourceId, true)
+                } else {
+                    viewedNewsResourceIds.remove(newsResourceId)
+                }
+            }
+        }
+    }
+
     suspend fun getChangeListVersions() = userPreferences.data
         .map {
             ChangeListVersions(
diff --git a/core/datastore/src/main/proto/com/google/samples/apps/nowinandroid/data/user_preferences.proto b/core/datastore/src/main/proto/com/google/samples/apps/nowinandroid/data/user_preferences.proto
index 5288c04ea..11386613c 100644
--- a/core/datastore/src/main/proto/com/google/samples/apps/nowinandroid/data/user_preferences.proto
+++ b/core/datastore/src/main/proto/com/google/samples/apps/nowinandroid/data/user_preferences.proto
@@ -40,6 +40,7 @@ message UserPreferences {
     map<string, bool> followed_topic_ids = 13;
     map<string, bool> followed_author_ids = 14;
     map<string, bool> bookmarked_news_resource_ids = 15;
+    map<string, bool> viewed_news_resource_ids = 20;
 
     ThemeBrandProto theme_brand = 16;
     DarkThemeConfigProto dark_theme_config = 17;
@@ -47,4 +48,6 @@ message UserPreferences {
     bool should_hide_onboarding = 18;
 
     bool use_dynamic_color = 19;
+
+    // NEXT AVAILABLE ID: 21
 }
diff --git a/core/domain/src/main/java/com/google/samples/apps/nowinandroid/core/domain/model/UserNewsResource.kt b/core/domain/src/main/java/com/google/samples/apps/nowinandroid/core/domain/model/UserNewsResource.kt
index 4e12ec95b..1d0051918 100644
--- a/core/domain/src/main/java/com/google/samples/apps/nowinandroid/core/domain/model/UserNewsResource.kt
+++ b/core/domain/src/main/java/com/google/samples/apps/nowinandroid/core/domain/model/UserNewsResource.kt
@@ -35,6 +35,7 @@ data class UserNewsResource internal constructor(
     val type: NewsResourceType,
     val followableTopics: List<FollowableTopic>,
     val isSaved: Boolean,
+    val isViewed: Boolean,
 ) {
     constructor(newsResource: NewsResource, userData: UserData) : this(
         id = newsResource.id,
@@ -51,6 +52,7 @@ data class UserNewsResource internal constructor(
             )
         },
         isSaved = userData.bookmarkedNewsResources.contains(newsResource.id),
+        isViewed = userData.viewedNewsResources.contains(newsResource.id),
     )
 }
 
diff --git a/core/domain/src/test/java/com/google/samples/apps/nowinandroid/core/domain/UserNewsResourceTest.kt b/core/domain/src/test/java/com/google/samples/apps/nowinandroid/core/domain/UserNewsResourceTest.kt
index 8350c5178..7931d3f80 100644
--- a/core/domain/src/test/java/com/google/samples/apps/nowinandroid/core/domain/UserNewsResourceTest.kt
+++ b/core/domain/src/test/java/com/google/samples/apps/nowinandroid/core/domain/UserNewsResourceTest.kt
@@ -68,6 +68,7 @@ class UserNewsResourceTest {
 
         val userData = UserData(
             bookmarkedNewsResources = setOf("N1"),
+            viewedNewsResources = setOf("N1"),
             followedTopics = setOf("T1"),
             themeBrand = DEFAULT,
             darkThemeConfig = FOLLOW_SYSTEM,
diff --git a/core/model/src/main/java/com/google/samples/apps/nowinandroid/core/model/data/UserData.kt b/core/model/src/main/java/com/google/samples/apps/nowinandroid/core/model/data/UserData.kt
index 638b90d36..6a22e4ff5 100644
--- a/core/model/src/main/java/com/google/samples/apps/nowinandroid/core/model/data/UserData.kt
+++ b/core/model/src/main/java/com/google/samples/apps/nowinandroid/core/model/data/UserData.kt
@@ -21,6 +21,7 @@ package com.google.samples.apps.nowinandroid.core.model.data
  */
 data class UserData(
     val bookmarkedNewsResources: Set<String>,
+    val viewedNewsResources: Set<String>,
     val followedTopics: Set<String>,
     val themeBrand: ThemeBrand,
     val darkThemeConfig: DarkThemeConfig,
diff --git a/core/testing/src/main/java/com/google/samples/apps/nowinandroid/core/testing/data/UserNewsResourcesTestData.kt b/core/testing/src/main/java/com/google/samples/apps/nowinandroid/core/testing/data/UserNewsResourcesTestData.kt
index 381160006..f4085d11e 100644
--- a/core/testing/src/main/java/com/google/samples/apps/nowinandroid/core/testing/data/UserNewsResourcesTestData.kt
+++ b/core/testing/src/main/java/com/google/samples/apps/nowinandroid/core/testing/data/UserNewsResourcesTestData.kt
@@ -30,6 +30,7 @@ import kotlinx.datetime.toInstant
 /* ktlint-disable max-line-length */
 val userNewsResourcesTestData: List<UserNewsResource> = UserData(
     bookmarkedNewsResources = setOf("1", "4"),
+    viewedNewsResources = setOf("1", "2", "4"),
     followedTopics = emptySet(),
     themeBrand = ThemeBrand.ANDROID,
     darkThemeConfig = DarkThemeConfig.DARK,
diff --git a/core/testing/src/main/java/com/google/samples/apps/nowinandroid/core/testing/repository/TestUserDataRepository.kt b/core/testing/src/main/java/com/google/samples/apps/nowinandroid/core/testing/repository/TestUserDataRepository.kt
index e1b86cd63..1b8483d1a 100644
--- a/core/testing/src/main/java/com/google/samples/apps/nowinandroid/core/testing/repository/TestUserDataRepository.kt
+++ b/core/testing/src/main/java/com/google/samples/apps/nowinandroid/core/testing/repository/TestUserDataRepository.kt
@@ -27,6 +27,7 @@ import kotlinx.coroutines.flow.filterNotNull
 
 val emptyUserData = UserData(
     bookmarkedNewsResources = emptySet(),
+    viewedNewsResources = emptySet(),
     followedTopics = emptySet(),
     themeBrand = ThemeBrand.DEFAULT,
     darkThemeConfig = DarkThemeConfig.FOLLOW_SYSTEM,
@@ -72,6 +73,21 @@ class TestUserDataRepository : UserDataRepository {
         }
     }
 
+    override suspend fun updateNewsResourceViewed(newsResourceId: String, viewed: Boolean) {
+        currentUserData.let { current ->
+            _userData.tryEmit(
+                current.copy(
+                    viewedNewsResources =
+                    if (viewed) {
+                        current.viewedNewsResources + newsResourceId
+                    } else {
+                        current.viewedNewsResources - newsResourceId
+                    },
+                ),
+            )
+        }
+    }
+
     override suspend fun setThemeBrand(themeBrand: ThemeBrand) {
         currentUserData.let { current ->
             _userData.tryEmit(current.copy(themeBrand = themeBrand))
diff --git a/core/ui/src/main/java/com/google/samples/apps/nowinandroid/core/ui/UserNewsResourcePreviewParameterProvider.kt b/core/ui/src/main/java/com/google/samples/apps/nowinandroid/core/ui/UserNewsResourcePreviewParameterProvider.kt
index e32aa1a57..8a1c108c6 100644
--- a/core/ui/src/main/java/com/google/samples/apps/nowinandroid/core/ui/UserNewsResourcePreviewParameterProvider.kt
+++ b/core/ui/src/main/java/com/google/samples/apps/nowinandroid/core/ui/UserNewsResourcePreviewParameterProvider.kt
@@ -40,6 +40,7 @@ class UserNewsResourcePreviewParameterProvider : PreviewParameterProvider<List<U
         get() {
             val userData: UserData = UserData(
                 bookmarkedNewsResources = setOf("1", "3"),
+                viewedNewsResources = setOf("1", "2", "4"),
                 followedTopics = emptySet(),
                 themeBrand = ThemeBrand.ANDROID,
                 darkThemeConfig = DarkThemeConfig.DARK,