This book constitutes the refereed proceedings of the 11th European Symposium on Research in Computer Security, ESORICS 2006, held in Hamburg, Germany, in September 2006.The 32 revised full papers presented were carefully reviewed and selected from 160 submissions. ESORICS is confirmed as the European research event in computer security; it presents original research contributions, case studies and implementation experiences addressing any aspect of computer security - in theory, mechanisms, applications, or practical experience.