diff --git a/domain/src/main/java/org/oppia/domain/classify/AnswerClassificationController.kt b/domain/src/main/java/org/oppia/domain/classify/AnswerClassificationController.kt
new file mode 100644
index 00000000000..e6dbfad25bd
--- /dev/null
+++ b/domain/src/main/java/org/oppia/domain/classify/AnswerClassificationController.kt
@@ -0,0 +1,26 @@
+package org.oppia.domain.classify
+
+import org.oppia.app.model.Interaction
+import org.oppia.app.model.InteractionObject
+import org.oppia.app.model.Outcome
+import javax.inject.Inject
+
+// TODO(#59): Restrict the visibility of this class to only other controllers.
+/**
+ * Controller responsible for classifying user answers to a specific outcome based on Oppia's interaction rule engine.
+ * This controller is not meant to be interacted with directly by the UI. Instead, UIs wanting to submit answers should
+ * do so via various progress controllers, like [StoryProgressController].
+ *
+ * This controller should only be interacted with via background threads.
+ */
+class AnswerClassificationController @Inject constructor() {
+  /**
+   * Classifies the specified answer in the context of the specified [Interaction] and returns the [Outcome] that best
+   * matches the learner's answer.
+   */
+  internal fun classify(interaction: Interaction, answer: InteractionObject): Outcome {
+    // Assume only the default outcome is returned currently since this stubbed implementation is not actually used by
+    // downstream stubbed progress controllers.
+    return interaction.defaultOutcome
+  }
+}
diff --git a/domain/src/test/java/org/oppia/domain/classify/AnswerClassificationControllerTest.kt b/domain/src/test/java/org/oppia/domain/classify/AnswerClassificationControllerTest.kt
new file mode 100644
index 00000000000..3f41de9c952
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+++ b/domain/src/test/java/org/oppia/domain/classify/AnswerClassificationControllerTest.kt
@@ -0,0 +1,121 @@
+package org.oppia.domain.classify
+
+import android.app.Application
+import android.content.Context
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.google.common.truth.Truth.assertThat
+import dagger.BindsInstance
+import dagger.Component
+import dagger.Module
+import dagger.Provides
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.oppia.app.model.AnswerGroup
+import org.oppia.app.model.Interaction
+import org.oppia.app.model.InteractionObject
+import org.oppia.app.model.Outcome
+import org.oppia.app.model.SubtitledHtml
+import org.robolectric.annotation.Config
+import javax.inject.Inject
+import javax.inject.Singleton
+
+/** Tests for [AnswerClassificationController]. */
+@RunWith(AndroidJUnit4::class)
+@Config(manifest = Config.NONE)
+class AnswerClassificationControllerTest {
+  private val ARBITRARY_SAMPLE_ANSWER = InteractionObject.newBuilder().setNormalizedString("Some value").build()
+
+  private val OUTCOME_0 = Outcome.newBuilder()
+    .setDestStateName("First state")
+    .setFeedback(SubtitledHtml.newBuilder().setContentId("content_id_0").setHtml("Feedback 1"))
+    .build()
+  private val OUTCOME_1 = Outcome.newBuilder()
+    .setDestStateName("Second state")
+    .setFeedback(SubtitledHtml.newBuilder().setContentId("content_id_1").setHtml("Feedback 2"))
+    .build()
+  private val OUTCOME_2 = Outcome.newBuilder()
+    .setDestStateName("Third state")
+    .setFeedback(SubtitledHtml.newBuilder().setContentId("content_id_2").setHtml("Feedback 3"))
+    .build()
+
+  @Inject
+  lateinit var answerClassificationController: AnswerClassificationController
+
+  @Before
+  fun setUp() {
+    setUpTestApplicationComponent()
+  }
+
+  @Test
+  fun testClassify_testInteraction_withOnlyDefaultOutcome_returnsDefaultOutcome() {
+    val interaction = Interaction.newBuilder()
+      .setDefaultOutcome(OUTCOME_0)
+      .build()
+
+    val outcome = answerClassificationController.classify(interaction, ARBITRARY_SAMPLE_ANSWER)
+
+    assertThat(outcome).isEqualTo(OUTCOME_0)
+  }
+
+  @Test
+  fun testClassify_testInteraction_withMultipleDefaultOutcomes_returnsDefaultOutcome() {
+    val interaction = Interaction.newBuilder()
+      .setDefaultOutcome(OUTCOME_1)
+      .addAnswerGroups(AnswerGroup.newBuilder().setOutcome(OUTCOME_2))
+      .build()
+
+    val outcome = answerClassificationController.classify(interaction, ARBITRARY_SAMPLE_ANSWER)
+
+    assertThat(outcome).isEqualTo(OUTCOME_1)
+  }
+
+  @Test
+  fun testClassify_afterPreviousInteraction_returnsDefaultOutcomeOfSecondInteraction() {
+    val interaction1 = Interaction.newBuilder()
+      .setDefaultOutcome(OUTCOME_1)
+      .addAnswerGroups(AnswerGroup.newBuilder().setOutcome(OUTCOME_0))
+      .build()
+    val interaction2 = Interaction.newBuilder()
+      .setDefaultOutcome(OUTCOME_2)
+      .build()
+    answerClassificationController.classify(interaction1, ARBITRARY_SAMPLE_ANSWER)
+
+    val outcome = answerClassificationController.classify(interaction2, ARBITRARY_SAMPLE_ANSWER)
+
+    assertThat(outcome).isEqualTo(OUTCOME_2)
+  }
+
+  private fun setUpTestApplicationComponent() {
+    DaggerAnswerClassificationControllerTest_TestApplicationComponent.builder()
+      .setApplication(ApplicationProvider.getApplicationContext())
+      .build()
+      .inject(this)
+  }
+
+  // TODO(#89): Move this to a common test application component.
+  @Module
+  class TestModule {
+    @Provides
+    @Singleton
+    fun provideContext(application: Application): Context {
+      return application
+    }
+  }
+
+  // TODO(#89): Move this to a common test application component.
+  @Singleton
+  @Component(modules = [TestModule::class])
+  interface TestApplicationComponent {
+    @Component.Builder
+    interface Builder {
+      @BindsInstance
+      fun setApplication(application: Application): Builder
+
+      fun build(): TestApplicationComponent
+    }
+
+    fun inject(answerClassificationControllerTest: AnswerClassificationControllerTest)
+  }
+}