This book constitutes the refereed proceedings of the 9th International Symposium on Stabilization, Safety, and Security of Distributed Systems, SSS 2007, held in Paris, France, November 14-16, 2007. The 27 regular papers presented together with the extended abstracts of three invited lectures were carefully reviewed and selected from 64 submissions. The papers address all aspects of self-stabilization, safety and security, recovery oriented systems and programming.