Systems and methods for combining streaming media content items for streaming to a client computer across a network are described. In one aspect, a playlist is maintained on a server computer. The playlist includes at least one reference to a streaming media content item and at least one placeholder. A request for a requested streaming media content item is received at the server computer from a client computer over a network. The server computer modifies the playlist to create a modified playlist by replacing at least one placeholder with a reference to a streaming media content item. This is accomplished such that the modified playlist includes at least one reference to the requested streaming media content item and at least one reference to at least one further streaming media content item. The streaming media content items referenced by the modified playlist are provided to the client computer over the network.