Peer-to-peer (P2P) systems, in which peer computers form a cooperative network and share their resources (storage, CPU, bandwidth), have attracted a lot of interest lately. After the apparition of the first truly successful P2P systems, and the significant amount of research conducted in Academia and in the Industry, most researchers now agree thatP2P systems are more than just a fashion phenomenon. They offer great potential for building cooperative networks that are self-organizing,efficient, scalable, and reliable.Research in P2P networks has so far mainly focused on content storage and lookup, but little work has been done about its actual distribution. By capitalizing the bandwidth of peer nodes, P2P architectures offer great potential for addressing some of the most challenging issue of today's Internet: the cost-effective distribution of bandwidth-intensive content to thousands of simultaneous users and the resilience to "flash crowds" (a huge and sudden surge of request traffic that usually leads to the collapse of the affected server). In this project, we propose to address the problem of cooperative distribution of streaming media and large content from a networking perspective. We plan to specifically focus on three complementary research directions: first, the design of topology-aware P2P substrates specialized for efficient content distribution; second, the push-based distribution of streaming content with timing constraints, such as streaming media (TV,radio); third, the pull-based distribution of large, but time-insensitive stored content. Each of these research topics will be supported upstream by extensive analysis and modeling, and downstream by prototype implementations and experimental validation.This project is expected to yield not only novel research contributions,but also practical techniques for cooperative content distribution applicable both Internet-wide and in large private networks. These techniques can be of great interest to media and infrastructure providers,as well as to medium and large companies that wish to avoid the cost of dedicated Content Delivery Networks (CDNs) for reliable content distribution.