diff --git a/src/libguac/client.c b/src/libguac/client.c
index 9738c0c2..29fb5b78 100644
--- a/src/libguac/client.c
+++ b/src/libguac/client.c
@@ -302,6 +302,10 @@ int guac_client_add_user(guac_client* client, guac_user* user, int argc, char**
         /* Update owner pointer if user is owner */
         if (user->owner)
             client->__owner = user;
+        
+        /* Notify owner of user joining connection. */
+        else
+            guac_client_owner_notify_join(client, user);
 
     }
 
@@ -331,6 +335,10 @@ void guac_client_remove_user(guac_client* client, guac_user* user) {
     if (user->owner)
         client->__owner = NULL;
 
+    /* Update owner of user having left the connection. */
+    else
+        guac_client_owner_notify_leave(client, user);
+
     pthread_rwlock_unlock(&(client->__users_lock));
 
     /* Call handler, if defined */
@@ -671,6 +679,36 @@ static void* __webp_support_callback(guac_user* user, void* data) {
 }
 #endif
 
+/**
+ * A callback function which is invoked by guac_client_owner_supports_msg()
+ * to determine if the owner of a client supports the "msg" instruction,
+ * returning zero if the user does not support the instruction or non-zero if
+ * the user supports it.
+ * 
+ * @param user
+ *     The guac_user that will be checked for "msg" instruction support.
+ * 
+ * @param data
+ *     Data provided to the callback. This value is never used within this
+ *     callback.
+ * 
+ * @return
+ *     A non-zero integer if the provided user who owns the connection supports
+ *     the "msg" instruction, or zero if the user does not. The integer is cast
+ *     as a void*.
+ */
+static void* guac_owner_supports_msg_callback(guac_user* user, void* data) {
+
+    return (void*) ((intptr_t) guac_user_supports_msg(user));
+
+}
+
+int guac_client_owner_supports_msg(guac_client* client) {
+
+    return (int) ((intptr_t) guac_client_for_owner(client, guac_owner_supports_msg_callback, NULL));
+
+}
+
 /**
  * A callback function which is invoked by guac_client_owner_supports_required()
  * to determine if the owner of a client supports the "required" instruction,
@@ -701,6 +739,124 @@ int guac_client_owner_supports_required(guac_client* client) {
     
 }
 
+/**
+ * A callback function that is invokved by guac_client_owner_notify_join() to
+ * notify the owner of a connection that another user has joined the
+ * connection, returning zero if the message is sent successfully, or non-zero
+ * if an error occurs.
+ *
+ * @param user
+ *     The user to send the notification to, which will be the owner of the
+ *     connection.
+ *
+ * @param data
+ *     The data provided to the callback, which is the user that is joining the
+ *     connection.
+ *
+ * @return
+ *     Zero if the message is sent successfully to the owner, otherwise
+ *     non-zero, cast as a void*.
+ */
+static void* guac_client_owner_notify_join_callback(guac_user* user, void* data) {
+
+    const guac_user* joiner = (const guac_user *) data;
+
+    if (user == NULL)
+        return (void*) ((intptr_t) -1);
+
+    char* log_owner = "owner";
+    if (user->info.name != NULL)
+        log_owner = (char *) user->info.name;
+
+    char* log_joiner = "anonymous";
+    char* send_joiner = "";
+    if (joiner->info.name != NULL) {
+        log_joiner = (char *) joiner->info.name;
+        send_joiner = (char *) joiner->info.name;
+    }
+
+    guac_user_log(user, GUAC_LOG_DEBUG, "Notifying owner \"%s\" of \"%s\" joining.",
+            log_owner, log_joiner);
+    
+    /* Send user joined notification to owner. */
+    const char* args[] = { (const char*)joiner->user_id, (const char*)send_joiner, NULL };
+    return (void*) ((intptr_t) guac_protocol_send_msg(user->socket, GUAC_MESSAGE_USER_JOINED, args));
+
+}
+
+int guac_client_owner_notify_join(guac_client* client, guac_user* joiner) {
+
+    /* Don't send msg instruction if client does not support it. */
+    if (!guac_client_owner_supports_msg(client)) {
+        guac_client_log(client, GUAC_LOG_DEBUG,
+                        "Client does not support the \"msg\" instruction and "
+                        "will not be notified of the user joining the connection.");
+        return -1;
+    }
+
+    return (int) ((intptr_t) guac_client_for_owner(client, guac_client_owner_notify_join_callback, joiner));
+
+}
+
+/**
+ * A callback function that is invokved by guac_client_owner_notify_leave() to
+ * notify the owner of a connection that another user has left the connection,
+ * returning zero if the message is sent successfully, or non-zero
+ * if an error occurs.
+ *
+ * @param user
+ *     The user to send the notification to, which will be the owner of the
+ *     connection.
+ *
+ * @param data
+ *     The data provided to the callback, which is the user that is leaving the
+ *     connection.
+ *
+ * @return
+ *     Zero if the message is sent successfully to the owner, otherwise
+ *     non-zero, cast as a void*.
+ */
+static void* guac_client_owner_notify_leave_callback(guac_user* user, void* data) {
+
+    const guac_user* quitter = (const guac_user *) data;
+
+    if (user == NULL)
+        return (void*) ((intptr_t) -1);
+
+    char* log_owner = "owner";
+    if (user->info.name != NULL)
+        log_owner = (char *) user->info.name;
+
+    char* log_quitter = "anonymous";
+    char* send_quitter = "";
+    if (quitter->info.name != NULL) {
+        log_quitter = (char *) quitter->info.name;
+        send_quitter = (char *) quitter->info.name;
+    }
+
+    guac_user_log(user, GUAC_LOG_DEBUG, "Notifying owner \"%s\" of \"%s\" leaving.",
+            log_owner, log_quitter);
+    
+    /* Send user left notification to owner. */
+    const char* args[] = { (const char*)quitter->user_id, (const char*)send_quitter, NULL };
+    return (void*) ((intptr_t) guac_protocol_send_msg(user->socket, GUAC_MESSAGE_USER_LEFT, args));
+
+}
+
+int guac_client_owner_notify_leave(guac_client* client, guac_user* quitter) {
+
+    /* Don't send msg instruction if client does not support it. */
+    if (!guac_client_owner_supports_msg(client)) {
+        guac_client_log(client, GUAC_LOG_DEBUG,
+                        "Client does not support the \"msg\" instruction and "
+                        "will not be notified of the user leaving the connection.");
+        return -1;
+    }
+
+    return (int) ((intptr_t) guac_client_for_owner(client, guac_client_owner_notify_leave_callback, quitter));
+
+}
+
 int guac_client_supports_webp(guac_client* client) {
 
 #ifdef ENABLE_WEBP
diff --git a/src/libguac/guacamole/client.h b/src/libguac/guacamole/client.h
index 4ffe5cf4..5712476f 100644
--- a/src/libguac/guacamole/client.h
+++ b/src/libguac/guacamole/client.h
@@ -708,6 +708,21 @@ void guac_client_stream_webp(guac_client* client, guac_socket* socket,
         guac_composite_mode mode, const guac_layer* layer, int x, int y,
         cairo_surface_t* surface, int quality, int lossless);
 
+/**
+ * Returns whether the owner of the given client supports the "msg"
+ * instruction, returning non-zero if the client owner does support the
+ * instruction, or zero if the owner does not.
+ * 
+ * @param client
+ *     The Guacamole client whose owner should be checked for supporting
+ *     the "msg" instruction.
+ * 
+ * @return 
+ *     Non-zero if the owner of the given client supports the "msg"
+ *     instruction, zero otherwise.
+ */
+int guac_client_owner_supports_msg(guac_client* client);
+
 /**
  * Returns whether the owner of the given client supports the "required"
  * instruction, returning non-zero if the client owner does support the
@@ -723,6 +738,42 @@ void guac_client_stream_webp(guac_client* client, guac_socket* socket,
  */
 int guac_client_owner_supports_required(guac_client* client);
 
+/**
+ * Notifies the owner of the given client that a user has joined the connection,
+ * and returns zero if the message was sent successfully, or non-zero if the
+ * notification failed.
+ *
+ * @param client
+ *     The Guacamole Client whose owner should be notified of a user joining
+ *     the connection.
+ *
+ * @param joiner
+ *     The Guacamole User who joined the connection.
+ * 
+ * @return
+ *     Zero if the notification to the owner was sent successfully, or non-zero
+ *     if an error occurred.
+ */
+int guac_client_owner_notify_join(guac_client* client, guac_user* joiner);
+
+/**
+ * Notifies the owner of the given client that a user has left the connection,
+ * and returns zero if the message was sent successfully, or non-zero if the
+ * notification failed.
+ *
+ * @param client
+ *     The Guacamole Client whose owner should be notified of a user leaving
+ *     the connection.
+ *
+ * @param quitter
+ *     The Guacamole User who left the connection.
+ * 
+ * @return
+ *     Zero if the notification to the owner was sent successfully, or non-zero
+ *     if an error occurred.
+ */
+int guac_client_owner_notify_leave(guac_client* client, guac_user* quitter);
+
 /**
  * Returns whether all users of the given client support WebP. If any user does
  * not support WebP, or the server cannot encode WebP images, zero is returned.
diff --git a/src/libguac/guacamole/protocol-constants.h b/src/libguac/guacamole/protocol-constants.h
index 13d7f680..a8fc9777 100644
--- a/src/libguac/guacamole/protocol-constants.h
+++ b/src/libguac/guacamole/protocol-constants.h
@@ -38,7 +38,7 @@
  * This version is passed by the __guac_protocol_send_args() function from the
  * server to the client during the client/server handshake.
  */
-#define GUACAMOLE_PROTOCOL_VERSION "VERSION_1_3_0"
+#define GUACAMOLE_PROTOCOL_VERSION "VERSION_1_5_0"
 
 /**
  * The maximum number of bytes that should be sent in any one blob instruction
diff --git a/src/libguac/guacamole/protocol-types.h b/src/libguac/guacamole/protocol-types.h
index 51652d2b..c943b431 100644
--- a/src/libguac/guacamole/protocol-types.h
+++ b/src/libguac/guacamole/protocol-types.h
@@ -306,9 +306,40 @@ typedef enum guac_protocol_version {
      * allowing connections in guacd to request information from the client and
      * await a response.
      */
-    GUAC_PROTOCOL_VERSION_1_3_0 = 0x010300
+    GUAC_PROTOCOL_VERSION_1_3_0 = 0x010300,
+
+    /**
+     * Protocol version 1.5.0, which supports the "msg" instruction, allowing
+     * messages to be sent to the client, and adds support for the "name"
+     * handshake instruction.
+     */
+    GUAC_PROTOCOL_VERSION_1_5_0 = 0x010500
 
 } guac_protocol_version;
 
+/**
+ * A type that represents codes for human-readable messages sent by the "msg"
+ * instruction to the Client, that will be displayed in the client's browser.
+ * The codes will be interpreted by the client into translatable messages, and
+ * make take arguments, as noted below.
+ */
+typedef enum guac_message_type {
+
+    /**
+     * A message that notifies the owner of a connection that another user has
+     * joined their connection. There should be a single argument provided, the
+     * name of the user who has joined.
+     */
+    GUAC_MESSAGE_USER_JOINED = 0x0001,
+
+    /**
+     * A message that notifies the owner of a connection that another user has
+     * left their connection. There should be a single argument provided, the
+     * name of the user who has left.
+     */
+    GUAC_MESSAGE_USER_LEFT = 0x0002
+
+} guac_message_type;
+
 #endif
 
diff --git a/src/libguac/guacamole/protocol.h b/src/libguac/guacamole/protocol.h
index 362351c5..91debdde 100644
--- a/src/libguac/guacamole/protocol.h
+++ b/src/libguac/guacamole/protocol.h
@@ -171,6 +171,27 @@ int guac_protocol_send_log(guac_socket* socket, const char* format, ...);
 int vguac_protocol_send_log(guac_socket* socket, const char* format,
         va_list args);
 
+/**
+ * Sends the given string over the socket to be displayed on the client. Returns
+ * zero if the message was sent successfully or non-zero if an error occurs.
+ *
+ * @param socket
+ *     The guac_socket connection to send the message to.
+ *
+ * @param msg
+ *     The message code to send to the client.
+ *
+ * @param args
+ *     A null-terminated array of strings that will be provided to the client
+ *     as part of the message, that the client may then place in the message,
+ *     or null if the message requires no arguments.
+ *
+ * @return
+ *     Zero if the message is sent successfully; otherwise non-zero.
+ */
+int guac_protocol_send_msg(guac_socket* socket, guac_message_type msg,
+        const char** args);
+
 /**
  * Sends a mouse instruction over the given guac_socket connection.
  *
diff --git a/src/libguac/guacamole/user.h b/src/libguac/guacamole/user.h
index 963dbe68..13fb146d 100644
--- a/src/libguac/guacamole/user.h
+++ b/src/libguac/guacamole/user.h
@@ -88,7 +88,7 @@ struct guac_user_info {
      * stated resolution of the display size request is recommended.
      */
     int optimal_resolution;
-    
+
     /**
      * The timezone of the remote system.  If the client does not provide
      * a specific timezone then this will be NULL.  The format of the timezone
@@ -102,6 +102,14 @@ struct guac_user_info {
      */
     guac_protocol_version protocol_version;
 
+    /**
+     * The human-readable name of the Guacamole user, supplied by the client
+     * during the handshake. This is an arbitrary value, with no requirements or
+     * constraints, including that it need not uniquely identify the user.
+     * If the client does not provide a name then this will be NULL.
+     */
+    const char* name;
+
 };
 
 struct guac_user {
@@ -850,6 +858,17 @@ void guac_user_stream_webp(guac_user* user, guac_socket* socket,
         guac_composite_mode mode, const guac_layer* layer, int x, int y,
         cairo_surface_t* surface, int quality, int lossless);
 
+/**
+ * Returns whether the given user supports the "msg" instruction.
+ * 
+ * @param user
+ *     The Guacamole user to check for support of the "msg" instruction.
+ * 
+ * @return 
+ *     Non-zero if the user supports the "msg" instruction, otherwise zero.
+ */
+int guac_user_supports_msg(guac_user* user);
+
 /**
  * Returns whether the given user supports the "required" instruction.
  * 
diff --git a/src/libguac/protocol.c b/src/libguac/protocol.c
index 1c53c200..3421af50 100644
--- a/src/libguac/protocol.c
+++ b/src/libguac/protocol.c
@@ -65,6 +65,7 @@ guac_protocol_version_mapping guac_protocol_version_table[] = {
     { GUAC_PROTOCOL_VERSION_1_0_0,   "VERSION_1_0_0" },
     { GUAC_PROTOCOL_VERSION_1_1_0,   "VERSION_1_1_0" },
     { GUAC_PROTOCOL_VERSION_1_3_0,   "VERSION_1_3_0" },
+    { GUAC_PROTOCOL_VERSION_1_5_0,   "VERSION_1_5_0" },
     { GUAC_PROTOCOL_VERSION_UNKNOWN, NULL }
 };
 
@@ -658,6 +659,23 @@ int guac_protocol_send_log(guac_socket* socket, const char* format, ...) {
 
 }
 
+int guac_protocol_send_msg(guac_socket* socket, guac_message_type msg,
+        const char** args) {
+
+    int ret_val;
+
+    guac_socket_instruction_begin(socket);
+    ret_val =
+           guac_socket_write_string(socket, "3.msg,")
+        || __guac_socket_write_length_int(socket, msg)
+        || guac_socket_write_array(socket, args)
+        || guac_socket_write_string(socket, ";");
+
+    guac_socket_instruction_end(socket);
+    return ret_val;
+
+}
+
 int guac_protocol_send_file(guac_socket* socket, const guac_stream* stream,
         const char* mimetype, const char* name) {
 
diff --git a/src/libguac/tests/protocol/guac_protocol_version.c b/src/libguac/tests/protocol/guac_protocol_version.c
index 37f42e0f..f9b2fdf2 100644
--- a/src/libguac/tests/protocol/guac_protocol_version.c
+++ b/src/libguac/tests/protocol/guac_protocol_version.c
@@ -27,11 +27,11 @@
  */
 void test_guac_protocol__version_to_string() {
     
-    guac_protocol_version version_a = GUAC_PROTOCOL_VERSION_1_3_0;
+    guac_protocol_version version_a = GUAC_PROTOCOL_VERSION_1_5_0;
     guac_protocol_version version_b = GUAC_PROTOCOL_VERSION_1_0_0;
     guac_protocol_version version_c = GUAC_PROTOCOL_VERSION_UNKNOWN;
     
-    CU_ASSERT_STRING_EQUAL(guac_protocol_version_to_string(version_a), "VERSION_1_3_0");
+    CU_ASSERT_STRING_EQUAL(guac_protocol_version_to_string(version_a), "VERSION_1_5_0");
     CU_ASSERT_STRING_EQUAL(guac_protocol_version_to_string(version_b), "VERSION_1_0_0");
     CU_ASSERT_PTR_NULL(guac_protocol_version_to_string(version_c));
     
diff --git a/src/libguac/user-handlers.c b/src/libguac/user-handlers.c
index c5cad9df..db1e7b8b 100644
--- a/src/libguac/user-handlers.c
+++ b/src/libguac/user-handlers.c
@@ -64,6 +64,7 @@ __guac_instruction_handler_mapping __guac_handshake_handler_map[] = {
     {"video",    __guac_handshake_video_handler},
     {"image",    __guac_handshake_image_handler},
     {"timezone", __guac_handshake_timezone_handler},
+    {"name",     __guac_handshake_name_handler},
     {NULL,       NULL}
 };
 
@@ -676,6 +677,23 @@ int __guac_handshake_image_handler(guac_user* user, int argc, char** argv) {
     
 }
 
+int __guac_handshake_name_handler(guac_user* user, int argc, char** argv) {
+
+    /* Free any past value for the user's name */
+    free((char *) user->info.name);
+
+    /* If a value is provided for the name, copy it into guac_user. */
+    if (argc > 0 && strcmp(argv[0], ""))
+        user->info.name = (const char*) strdup(argv[0]);
+
+    /* No or empty value was provided, so make sure this is NULLed out. */
+    else
+        user->info.name = NULL;
+
+    return 0;
+
+}
+
 int __guac_handshake_timezone_handler(guac_user* user, int argc, char** argv) {
     
     /* Free any past value */
diff --git a/src/libguac/user-handlers.h b/src/libguac/user-handlers.h
index a51a3f89..7f82302b 100644
--- a/src/libguac/user-handlers.h
+++ b/src/libguac/user-handlers.h
@@ -218,6 +218,13 @@ __guac_instruction_handler __guac_handshake_video_handler;
  */
 __guac_instruction_handler __guac_handshake_image_handler;
 
+/**
+ * Internal handler function that is called when the name instruction is
+ * received during the handshake process, specifying the name of the Guacamole
+ * user establishing the connection.
+ */
+__guac_instruction_handler __guac_handshake_name_handler;
+
 /**
  * Internal handler function that is called when the timezone instruction is
  * received during the handshake process, specifying the timezone of the
diff --git a/src/libguac/user-handshake.c b/src/libguac/user-handshake.c
index 4e0fa446..0863325f 100644
--- a/src/libguac/user-handshake.c
+++ b/src/libguac/user-handshake.c
@@ -296,6 +296,7 @@ int guac_user_handle_connection(guac_user* user, int usec_timeout) {
     user->info.audio_mimetypes = NULL;
     user->info.image_mimetypes = NULL;
     user->info.video_mimetypes = NULL;
+    user->info.name = NULL;
     user->info.timezone = NULL;
     
     /* Count number of arguments. */
@@ -370,7 +371,8 @@ int guac_user_handle_connection(guac_user* user, int usec_timeout) {
     guac_free_mimetypes((char **) user->info.image_mimetypes);
     guac_free_mimetypes((char **) user->info.video_mimetypes);
     
-    /* Free timezone info. */
+    /* Free name and timezone info. */
+    free((char *) user->info.name);
     free((char *) user->info.timezone);
     
     guac_parser_free(parser);
diff --git a/src/libguac/user.c b/src/libguac/user.c
index 4320ca77..d16f43b9 100644
--- a/src/libguac/user.c
+++ b/src/libguac/user.c
@@ -316,6 +316,15 @@ void guac_user_stream_webp(guac_user* user, guac_socket* socket,
 
 }
 
+int guac_user_supports_msg(guac_user* user) {
+
+    if (user == NULL)
+        return 0;
+
+    return (user->info.protocol_version >= GUAC_PROTOCOL_VERSION_1_5_0);
+
+}
+
 int guac_user_supports_required(guac_user* user) {
     
     if (user == NULL)