As software systems become ubiquitous, the issues of dependability become more and more critical. Given that solutions to these issues must be taken into account from the very beginning of the design process, it is appropriate that dependability is addressed at the architectural level. This book results from an effort to bring together the research communities of software architectures and dependability. Inspired by the ICSE 2003 Workshop on Software Architectures for Dependable Systems, the book focuses on topics relevant to improving the state of the art in architecting dependable systems. The 15 thoroughly reviewed papers originate partly from the workshop; others were solicited in order to