This book constitutes the thoroughly refereed post-proceedings of the annual International Conference on Computational Intelligence and Security, CIS 2006, held in Guangzhou, China in November 2006. The 116 revised papers presented were carefully reviewed and selected from a total of 2078 initial submissions during two rounds of revision and improvement. The papers are organized in topical sections on bio-inspired computing, evolutionary computation, learning systems and multi-agents, cryptography, information processing and intrusion detection, systems and security, image and signal processing, as well as pattern recognition.