The design of innovative products and services that take advantage of Systems of Systems (SoS) technology is in its infancy. It is hampered by the complexity caused by the heterogeneity and independence of SoS constituent systems and the difficulty of communication between diverse stakeholders. The state of the art in SoS engineering lacks models and tools that help developers to make trade-off decisions during design and evolution, and assist in working out and recording precise contracts between constituents and the global SoS. This leads to sub-optimal design and expensive rework during integration and in service.COMPASS will augment existing industry tools and practice with an underlying modelling language in which SoS architectures and contracts can be expressed. A formal semantic foundation – the first to be developed specifically for SoS engineering – will enable this language to support analysis of global SoS properties. The language and methods will be supported by an open, extendible tools platform with integrated prototype plug-ins for model construction, dynamic analysis by simulation and test automation, static analysis by model-checking and proof, and links to an established architectural modelling language (SysML). These strengthened foundations and tools will support enhanced methods guidelines that help users embed this new technology in industrial SoS practice.Technical advances in COMPASS are focussed on industry needs evaluated through substantial industry-led case studies in three diverse and complementary areas. These will be augmented by challenge problems solicited from a range of SoS stakeholders and developer organisations through a special interest group. The open platform, tools plug-ins, semantics, development guidelines, industry case study experience and challenge problems will ensure that COMPASS's outputs can be readily exploited by SoS developers and stakeholders as well as in future research and development.