Advertisements or other types of targeted information are delivered to set-top boxes or other user interface devices of a signal distribution system. In one aspect of the invention, an access node sends a message to the user interface device directing the user interface device to switch from a content stream to a targeted information stream at a specified time. Responsive to the message, the access node receives a request from the user interface device to join a targeted multicast group associated with the targeted information stream. Without requiring receipt of a subsequent request from the user interface device to leave a content multicast group associated with a content stream, the access node causes the user interface device to be dropped from the content multicast group prior to the specified time. The access node then delivers the targeted information stream to the user interface device via the targeted multicast group.