Abstract. Recently, development of peer-to-peer (P2P) applications has been giving a paramount attention mostly due to their attractive features such as decentralization and self-organization. Providing the programmer with the “right” platform for developing such applications became a challenge. In this paper we describe the functionality of P2PS, a platform for developing P2P applications in Mozart. The P2PS platform provides the developer with a means for building and working with P2P overlay applications, offering different primitives and services such as group communication, efficient data location, and dealing with highly dynamic networks. P2PS implements Tango, an efficient algorithm for constructing structured P2P systems. It is delivered as a library and already made public, being used as underlying structure for different P2P applications.