diff --git a/java/com/google/gerrit/extensions/validators/CommentForValidation.java b/java/com/google/gerrit/extensions/validators/CommentForValidation.java
new file mode 100644
index 0000000..51ae5ae
--- /dev/null
+++ b/java/com/google/gerrit/extensions/validators/CommentForValidation.java
@@ -0,0 +1,48 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.extensions.validators;
+
+import com.google.auto.value.AutoValue;
+
+/**
+ * Holds a comment's text and {@link CommentType} in order to pass it to a validation plugin.
+ *
+ * @see CommentValidator
+ */
+@AutoValue
+public abstract class CommentForValidation {
+
+  /** The type of comment. */
+  public enum CommentType {
+    /** A regular (inline) comment. */
+    INLINE_COMMENT,
+    /** A file comment. */
+    FILE_COMMENT,
+    /** A change message. */
+    CHANGE_MESSAGE
+  }
+
+  public static CommentForValidation create(CommentType type, String text) {
+    return new AutoValue_CommentForValidation(type, text);
+  }
+
+  public abstract CommentType getType();
+
+  public abstract String getText();
+
+  public CommentValidationFailure failValidation(String message) {
+    return CommentValidationFailure.create(this, message);
+  }
+}
diff --git a/java/com/google/gerrit/extensions/validators/CommentValidationFailure.java b/java/com/google/gerrit/extensions/validators/CommentValidationFailure.java
new file mode 100644
index 0000000..1a832760
--- /dev/null
+++ b/java/com/google/gerrit/extensions/validators/CommentValidationFailure.java
@@ -0,0 +1,32 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.extensions.validators;
+
+import com.google.auto.value.AutoValue;
+
+/** A comment or review message was rejected by a {@link CommentValidator}. */
+@AutoValue
+public abstract class CommentValidationFailure {
+  static CommentValidationFailure create(
+      CommentForValidation commentForValidation, String message) {
+    return new AutoValue_CommentValidationFailure(commentForValidation, message);
+  }
+
+  /** Returns the offending comment. */
+  public abstract CommentForValidation getComment();
+
+  /** A friendly message set by the {@link CommentValidator}. */
+  public abstract String getMessage();
+}
diff --git a/java/com/google/gerrit/extensions/validators/CommentValidator.java b/java/com/google/gerrit/extensions/validators/CommentValidator.java
new file mode 100644
index 0000000..cbcf1a9
--- /dev/null
+++ b/java/com/google/gerrit/extensions/validators/CommentValidator.java
@@ -0,0 +1,34 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.extensions.validators;
+
+import com.google.common.collect.ImmutableList;
+import com.google.gerrit.extensions.annotations.ExtensionPoint;
+
+/**
+ * Validates review comments and messages. Rejecting any comment/message will prevent all comments
+ * from being published.
+ */
+@ExtensionPoint
+public interface CommentValidator {
+
+  /**
+   * Validate the specified commits.
+   *
+   * @return An empty list if all commits are valid, or else a list of validation failures.
+   */
+  ImmutableList<CommentValidationFailure> validateComments(
+      ImmutableList<CommentForValidation> comments);
+}
diff --git a/java/com/google/gerrit/server/config/GerritGlobalModule.java b/java/com/google/gerrit/server/config/GerritGlobalModule.java
index 14747e5..478cf8f 100644
--- a/java/com/google/gerrit/server/config/GerritGlobalModule.java
+++ b/java/com/google/gerrit/server/config/GerritGlobalModule.java
@@ -62,6 +62,7 @@
 import com.google.gerrit.extensions.registration.DynamicMap;
 import com.google.gerrit.extensions.registration.DynamicSet;
 import com.google.gerrit.extensions.systemstatus.MessageOfTheDay;
+import com.google.gerrit.extensions.validators.CommentValidator;
 import com.google.gerrit.extensions.webui.BranchWebLink;
 import com.google.gerrit.extensions.webui.DiffWebLink;
 import com.google.gerrit.extensions.webui.FileHistoryWebLink;
@@ -341,6 +342,7 @@
     DynamicSet.bind(binder(), EventListener.class).to(EventsMetrics.class);
     DynamicSet.setOf(binder(), UserScopedEventListener.class);
     DynamicSet.setOf(binder(), CommitValidationListener.class);
+    DynamicSet.setOf(binder(), CommentValidator.class);
     DynamicSet.setOf(binder(), ChangeMessageModifier.class);
     DynamicSet.setOf(binder(), RefOperationValidationListener.class);
     DynamicSet.setOf(binder(), OnSubmitValidationListener.class);