In this paper, we propose ScaleStream, a new algorithm to support scalable multimedia streaming in peer-to-peer networks, under strict resources constraints. With the growth of multimedia consumption over the Internet, achieving scalability in a resource-constrained environment is indeed becoming a critical requirement. Intuitively, our approach consists in dynamically replicating the multimedia content being streamed, based on bandwidth and memory constraints. Our replication management strategy maximizes the number of consumers being served concurrently, while minimizing memory usage, under strict bandwidth constraints.