diff --git a/my_project_name/bot_commands.py b/my_project_name/bot_commands.py
index 1dfa608..d9a40db 100644
--- a/my_project_name/bot_commands.py
+++ b/my_project_name/bot_commands.py
@@ -1,4 +1,4 @@
-from my_project_name.chat_functions import send_text_to_room
+from my_project_name.chat_functions import react_to_event, send_text_to_room
 
 
 class Command(object):
@@ -30,6 +30,8 @@ class Command(object):
         """Process the command"""
         if self.command.startswith("echo"):
             await self._echo()
+        elif self.command.startswith("react"):
+            await self._react()
         elif self.command.startswith("help"):
             await self._show_help()
         else:
@@ -40,6 +42,20 @@ class Command(object):
         response = " ".join(self.args)
         await send_text_to_room(self.client, self.room.room_id, response)
 
+    async def _react(self):
+        """Make the bot react to the command message"""
+        # React with a start emoji
+        reaction = "⭐"
+        await react_to_event(
+            self.client, self.room.room_id, self.event.event_id, reaction
+        )
+
+        # React with some generic text
+        reaction = "Some text"
+        await react_to_event(
+            self.client, self.room.room_id, self.event.event_id, reaction
+        )
+
     async def _show_help(self):
         """Show the help text"""
         if not self.args:
diff --git a/my_project_name/callbacks.py b/my_project_name/callbacks.py
index 7152e64..a7443ec 100644
--- a/my_project_name/callbacks.py
+++ b/my_project_name/callbacks.py
@@ -1,8 +1,9 @@
 import logging
 
-from nio import JoinError
+from nio import JoinError, MatrixRoom, RoomGetEventError, UnknownEvent
 
 from my_project_name.bot_commands import Command
+from my_project_name.chat_functions import make_pill, send_text_to_room
 from my_project_name.message_responses import Message
 
 logger = logging.getLogger(__name__)
@@ -86,3 +87,66 @@ class Callbacks(object):
 
         # Successfully joined room
         logger.info(f"Joined {room.room_id}")
+
+    async def _reaction(
+        self, room: MatrixRoom, event: UnknownEvent, reacted_to_id: str
+    ):
+        """A reaction was sent to one of our messages. Let's send a reply acknowledging it.
+
+        Args:
+            room: The room the reaction was sent in.
+
+            event: The reaction event.
+
+            reacted_to_id: The event ID that the reaction points to.
+        """
+        logger.debug(f"Got reaction to {room.room_id} from {event.sender}.")
+
+        # Get the original event that was reacted to
+        event_response = await self.client.room_get_event(room.room_id, reacted_to_id)
+        if isinstance(event_response, RoomGetEventError):
+            logger.warning(
+                "Error getting event that was reacted to (%s)", reacted_to_id
+            )
+            return
+        reacted_to_event = event_response.event
+
+        # Only acknowledge reactions to events that we sent
+        if reacted_to_event.sender != self.config.user_id:
+            return
+
+        # Send a message acknowledging the reaction
+        reaction_sender_pill = make_pill(event.sender)
+        reaction_content = (
+            event.source.get("content", {}).get("m.relates_to", {}).get("key")
+        )
+        message = (
+            f"{reaction_sender_pill} reacted to this event with `{reaction_content}`!"
+        )
+        await send_text_to_room(
+            self.client,
+            room.room_id,
+            message,
+            reply_to_event_id=reacted_to_id,
+        )
+
+    async def unknown(self, room: MatrixRoom, event: UnknownEvent):
+        """Callback for when an event with a type that is unknown to matrix-nio is received.
+        Currently this is used for reaction events, which are not specced.
+
+        Args:
+            room: The room the reaction was sent in.
+
+            event: The reaction event.
+        """
+        if event.type == "m.reaction":
+            # Get the ID of the event this was a reaction to
+            relation_dict = event.source.get("content", {}).get("m.relates_to", {})
+
+            reacted_to = relation_dict.get("event_id")
+            if reacted_to and relation_dict.get("rel_type") == "m.annotation":
+                await self._reaction(room, event, reacted_to)
+
+        logger.debug(
+            f"Got unknown event with type to {event.type} from {event.sender} in {room.room_id}."
+        )
diff --git a/my_project_name/chat_functions.py b/my_project_name/chat_functions.py
index 7e480a8..87038fb 100644
--- a/my_project_name/chat_functions.py
+++ b/my_project_name/chat_functions.py
@@ -1,28 +1,37 @@
 import logging
+from typing import Optional, Union
 
 from markdown import markdown
-from nio import SendRetryError
+from nio import AsyncClient, ErrorResponse, Response, SendRetryError
 
 logger = logging.getLogger(__name__)
 
 
 async def send_text_to_room(
-    client, room_id, message, notice=True, markdown_convert=True
+    client: AsyncClient,
+    room_id: str,
+    message: str,
+    notice: bool = True,
+    markdown_convert: bool = True,
+    reply_to_event_id: Optional[str] = None,
 ):
-    """Send text to a matrix room
+    """Send text to a matrix room.
 
     Args:
-        client (nio.AsyncClient): The client to communicate to matrix with
+        client: The client to communicate to matrix with.
 
-        room_id (str): The ID of the room to send the message to
+        room_id: The ID of the room to send the message to.
 
-        message (str): The message content
+        message: The message content.
 
-        notice (bool): Whether the message should be sent with an "m.notice" message type
-            (will not ping users)
+        notice: Whether the message should be sent with an "m.notice" message type
+            (will not ping users).
 
-        markdown_convert (bool): Whether to convert the message content to markdown.
+        markdown_convert: Whether to convert the message content to markdown.
             Defaults to true.
+
+        reply_to_event_id: Whether this message is a reply to another event. The event
+            ID this is message is a reply to.
     """
     # Determine whether to ping room members or not
     msgtype = "m.notice" if notice else "m.text"
@@ -36,9 +45,74 @@ async def send_text_to_room(
     if markdown_convert:
         content["formatted_body"] = markdown(message)
 
+    if reply_to_event_id:
+        content["m.relates_to"] = {"m.in_reply_to": {"event_id": reply_to_event_id}}
+
     try:
         await client.room_send(
-            room_id, "m.room.message", content, ignore_unverified_devices=True,
+            room_id,
+            "m.room.message",
+            content,
+            ignore_unverified_devices=True,
         )
     except SendRetryError:
         logger.exception(f"Unable to send message response to {room_id}")
+
+
+def make_pill(user_id: str, displayname: str = None) -> str:
+    """Convert a user ID (and optionally a display name) to a formatted user 'pill'
+
+    Args:
+        user_id: The MXID of the user.
+
+        displayname: An optional displayname. Clients like Element will figure out the
+            correct display name no matter what, but other clients may not. If not
+            provided, the MXID will be used instead.
+
+    Returns:
+        The formatted user pill.
+    """
+    if not displayname:
+        # Use the user ID as the displayname if not provided
+        displayname = user_id
+
+    return f'<a href="https://matrix.to/#/{user_id}">{displayname}</a>'
+
+
+async def react_to_event(
+    client: AsyncClient,
+    room_id: str,
+    event_id: str,
+    reaction_text: str,
+) -> Union[Response, ErrorResponse]:
+    """Reacts to a given event in a room with the given reaction text
+
+    Args:
+        client: The client to communicate to matrix with.
+
+        room_id: The ID of the room to send the message to.
+
+        event_id: The ID of the event to react to.
+
+        reaction_text: The string to react with. Can also be (one or more) emoji characters.
+
+    Returns:
+        A nio.Response or nio.ErrorResponse if an error occurred.
+
+    Raises:
+        SendRetryError: If the reaction was unable to be sent.
+    """
+    content = {
+        "m.relates_to": {
+            "rel_type": "m.annotation",
+            "event_id": event_id,
+            "key": reaction_text,
+        }
+    }
+
+    return await client.room_send(
+        room_id,
+        "m.reaction",
+        content,
+        ignore_unverified_devices=True,
+    )
diff --git a/my_project_name/main.py b/my_project_name/main.py
index f3173ef..732340b 100644
--- a/my_project_name/main.py
+++ b/my_project_name/main.py
@@ -12,6 +12,7 @@ from nio import (
     LocalProtocolError,
     LoginError,
     RoomMessageText,
+    UnknownEvent,
 )
 
 from my_project_name.callbacks import Callbacks
@@ -59,6 +60,7 @@ async def main():
     callbacks = Callbacks(client, store, config)
     client.add_event_callback(callbacks.message, (RoomMessageText,))
     client.add_event_callback(callbacks.invite, (InviteMemberEvent,))
+    client.add_event_callback(callbacks.unknown, (UnknownEvent,))
 
     # Keep trying to reconnect on failure (with some time in-between)
     while True:
@@ -74,7 +76,8 @@ async def main():
                 # Try to login with the configured username/password
                 try:
                     login_response = await client.login(
-                        password=config.user_password, device_name=config.device_name,
+                        password=config.user_password,
+                        device_name=config.device_name,
                     )
 
                     # Check if login failed