This book constitutes the thoroughly refereed post-proceedings of the Third International Service Availability Symposium, ISAS 2006, held in Helsinki, Finland, in May 2006.

The 19 revised full papers presented were carefully reviewed and selected from 38 submissions. The papers are organized in topical sections on availability modeling, estimation and analysis, dependability techniques and their applications, performability: measurements and assessments, service availability standards: experience reports and futures.