|The DSoS Project contributes towards the objectives of CPA 2, the Cross-Programme Action on Dependability. It will produce methods and tools for the dependable composition of a "system of systems" (SoS) from a set of diverse, heterogenous and autonomous systems. A SoS provides new emerging services to its users, in addition to the services provided by its component systems. This project aims to ensure that both types of services are provided with a level of dependability matching specified user requirements. There is a number of existing, and many planned, such SoSs, on which industry, the public at large, and governments will place great dependence. Ensuring that, as far as humanly possible, such systems exhibit a level of dependability that is at least commensurate with the dependence to be placed on them poses major challenges to present theory and practice related to computer system design, validation, integration and management.