This book constitutes the refereed proceedings of the Second International Workshop on Self-Organizing Systems, IWSOS 2007, held in The Lake District, UK, September 11-13, 2007.

The 17 revised full papers and 5 revised short papers presented together with 2 invited talks were carefully selected from more than 36 submissions. The papers are organized in topical sections on ad hoc routing, peer-to-peer networking, network topology, adaptive and self-organizing networks and multicast and mobility protocols.