Written for hardware-software system engineers, researchers and students, this text introduces a systems engineering method that guides the development of software and embedded hardware-software systems seamlessly from requirements capture to their implementation. It helps the designer to cope with the three stumbling-blocks of building modern software based systems: size, complexity and trustworthiness. It covers within a single conceptual framework both design, verification by reasoning techniques, and experimental validation by simulation and testing. The text contains detailed proofs, exercises, as well as numerous real-world examples and case studies.