This book constitutes the refereed proceedings of the 21st International Conference on Computer Safety, Reliability and Security, SAFECOMP 2002, held in Catania, Italy in September 2002.The 27 revised papers presented together with 3 keynote presentations were carefully reviewed and selected from 69 submissions. The papers are organized in topical sections on human-computer system dependability, human factors, security, dependability assessment, application of formal methods, reliability assessment, design for dependability, and safety assessment.