— The peer-to-peer communication paradigm, when used to disseminate bulk content or to stream real-time multimedia, has enjoyed the distinct advantage of scalability when compared to the client-server model, since it takes advantage of available upload bandwidth at participating peers to alleviate server load. As multiple concurrent peer-to-peer sessions co-exist in the Internet, it is natural to demand differentiated services in different sessions, with respect to Quality of Service metrics such as bit rates and latencies. The problem of service differentiation across sessions, however, has never been addressed in the literature at the application layer. In this paper, we open a new direction of research that treats different peer-to-peer sessions with different priorities, and present Diverse, a novel applicationlayer approach to achieve service differentiation across different sessions. An extensive evaluation of our implementation of Diverse in an emulated peer-to-peer environmen...