At a client device, a user subscribes to a specified stream, where the specified stream includes one or more other streams. A respective stream of the one or more other streams includes two or more content feeds, and each content feed includes a set of content items published by a respective publication source. The client devices presents to the user (e.g., on a display of the client device) content items associated with the specified stream. In some embodiments, streams can be recursively defined to include combinations of other streams, and users who subscribe to a recursively defined stream receive content items from the content feeds associated with that stream.