This new book addresses the status of the field of System Dynamics 60+ years after its inception. It presents state-of-the-art expositions by leading authorities in either a facet of the theory and methodology of the subject or its application in a specific domain. Exhibiting greater reach and authority than would be possible in a conventional authored textbook, the volume includes nine chapters covering methodological aspects, and 14 on various contemporary applications. Emerging from the System Dynamics section of the Encyclopedia of Complexity & Systems Science, First Edition (2009), the book features brand new chapters covering project management, workforce modelling, applications in defense, operations management, engineering of strategy, the roots of model validation, as well as many considerably enhanced versions of existing chapters. Together, the chapters reveal a remarkable landscape of theory and practice, and how System Dynamics can contribute critical policy insights to a broad audience of students and professionals across many fields of study.