We study a scalable and efficient end host multicast-DSCT (Dynamic Shared Cluster Tree) for P2P systems in this paper. In our design, we focus on making full use of underlying physical properties to improve both scalability and efficiency as data multicast in the overlay topologies of P2P systems. In this paper, we present the DSCT architecture, the dynamic scheme to select cluster cores according to the instantaneous network situations. These are all the key points to construct the basic DSCT (BDSCT) multicast. Through further studies, we provide DSCT improvement design (IDSCT) to make it more suitable for multiple-source P2P communications. Our simulation results indicate that it is possible to improve the scalability and efficiency of end host multicast in P2P systems by using our DSCT designs. © 2004 IEEE.