As software systems become ubiquitous, the issues of dependability become more and more crucial. Given that solutions to these issues must be considered from the very beginning of the design process, it is reasonable that dependability is addressed at the architectural level. This book comes as a result of an effort to bring together the research communities of software architectures and dependability. This state-of-the-art survey contains 16 carefully selected papers originating from the Twin Workshops on Architecting Dependable Systems (WADS 2004) accomplished as part of the International Conference on Software Engineering (ICSE 2004) in Edinburgh, UK and of the International Conference on Dependable Systems and Networks (DSN 2004) in Florence, Italy. The papers are organised in topical sections on architectures for dependable services, monitoring and reconfiguration in software architectures, dependability support for software architectures, architectural evaluation, and architectural abstractions for dependability.