COMBEST will provide a formal framework for component based design of complex embedded systems. This framework will:1.\tEnable formal integration of heterogeneous components, such as with different models of communication or execution;2.\tProvide complete encapsulation of components both for functional and extra-functional properties and develop foundations and methods ensuring composability of components;3.\tEnable prediction of emergent key system characteristics such as performance and robustness (timing, safety) from such characterizations of its subcomponents;4.\tProvide certificates for guarantees of such key system characteristics when deployed on distributed HW-architecturesTo achieve these objectives, COMBEST will:•\tDevelop a design theory for complex embedded systems, fully covering heterogeneity, interface specifications, composability, compositionality, and refinement for functional and extra-functional properties•\tBuild on substantial highly recognized background results of the academic partners, partly carried out within the integrated projet SPEEDS;•\tExtend results of the Integrated Project SPEEDS, both regarding heterogeneous rich components and compositional analysis methods.•\tCollaborate with the best US groups in embedded system design to build critical mass in a strategic area of vital interest to the European industrial ecosystem.