Contribution-Aware Overlay Optimization for Peer-to-Peer Live Streaming Applications In this paper, we study how to optimize mesh-based overlay in a contribution aware manner. We have designed a suite of protocols to construct and optimize the overlay. Our core idea is to promote nodes with larger contribution closer to the source node so as to keep a compact and efficient mesh-basedstreaming overlay. Our method is evaluated through extensive simulations. Compared with the non-optimized overlay, the p2p streaming applications using our method could cut down the average latency by 20-50% and enhanced the continuity index up to 120%.