diff --git a/backend/add_parent_id_column.py b/backend/add_parent_id_column.py
new file mode 100644
index 0000000..4f244ff
--- /dev/null
+++ b/backend/add_parent_id_column.py
@@ -0,0 +1,15 @@
+from sqlmodel import Session, create_engine, text
+from database import DATABASE_URL
+
+def add_column():
+    engine = create_engine(DATABASE_URL)
+    with Session(engine) as session:
+        try:
+            session.exec(text("ALTER TABLE comment ADD COLUMN parent_id INTEGER REFERENCES comment(id)"))
+            session.commit()
+            print("Successfully added parent_id column to comment table")
+        except Exception as e:
+            print(f"Error adding column (might already exist): {e}")
+
+if __name__ == "__main__":
+    add_column()
diff --git a/backend/models.py b/backend/models.py
index f7a3781..58391b5 100644
--- a/backend/models.py
+++ b/backend/models.py
@@ -138,6 +138,7 @@ class Comment(SQLModel, table=True):
     show_id: Optional[int] = Field(default=None, foreign_key="show.id")
     venue_id: Optional[int] = Field(default=None, foreign_key="venue.id")
     song_id: Optional[int] = Field(default=None, foreign_key="song.id")
+    parent_id: Optional[int] = Field(default=None, foreign_key="comment.id")
     
     user: "User" = Relationship(back_populates="comments")
 
diff --git a/backend/routers/social.py b/backend/routers/social.py
index 955e37f..fef693e 100644
--- a/backend/routers/social.py
+++ b/backend/routers/social.py
@@ -24,8 +24,18 @@ def create_comment(
     session.commit()
     session.refresh(db_comment)
     
-    # Notify parent author if reply (TODO: Add parent_id to Comment model)
-    # For now, let's just log it or skip.
+    # Notify parent author if reply
+    if db_comment.parent_id:
+        parent_comment = session.get(Comment, db_comment.parent_id)
+        if parent_comment and parent_comment.user_id != current_user.id:
+            create_notification(
+                session,
+                user_id=parent_comment.user_id,
+                title="New Reply",
+                message=f"Someone replied to your comment.",
+                type="reply",
+                link=f"/activity"
+            )
     
     # Handle Mentions
     mention_pattern = r"@(\w+)"
diff --git a/backend/schemas.py b/backend/schemas.py
index aefb2f2..29f790f 100644
--- a/backend/schemas.py
+++ b/backend/schemas.py
@@ -207,6 +207,7 @@ class CommentBase(SQLModel):
     show_id: Optional[int] = None
     venue_id: Optional[int] = None
     song_id: Optional[int] = None
+    parent_id: Optional[int] = None
 
 class CommentCreate(CommentBase):
     pass