We describe the design and implementation of CoDD, a system for cooperative data dissemination in a serverless environment. CoDD allows a set of loosely-coupled, distributed peer nodes to receive subsets of a data stream, by describing interests using subscription queries. CoDD maintains statistical information on the characteristics of data and queries, and uses it to organize nodes in a hierarchical, data-aware topology. Data is disseminated using overlays which are created to try to minimize the excess data flowing through the system, while maintaining low latency and satisfying fanout constraints. CoDD is designed to allow nodes to determine individual degrees of contribution to the system, and to adapt gracefully to temporal changes in the data distribution using an adaptive reorganization component. We present the results of our experimental evaluation of CoDD. (UMIACS-TR-2004-07)