In the modern world most gross product is created within Enterprise firms; project programs; state agencies; transnational corporations and their divisions, as well as various associations and compositions of all of the above entities. Enterprises being, on the one hand, complex, and, on the other hand, widespread systems, are in the focus of cybernetics, system theory, operations research, management sciences and many other fields of knowledge. However, the complexity of the system obstructs the development of mathematically rigorous foundations for Enterprise control. Moreover, methods of operations research and related sciences, widely used in practice, provide optimization of constituents of an Enterprise, without modeling it as a whole system. But the optimization of parts does not lead to the optimality of the whole, and also the absence of top-down and holistic mathematical models of Enterprise contradicts the principle of holism and the system approach. The approach in this book looks firstly at Enterprise Systems, and their essential aspects,  as complex sociotechnical systems composed of integrated sets of structural and process models (Chapter 1 and 2). A uniform description of all the heterogeneous fields of the modern Enterprise (marketing, sales, manufacturing, HR, finance, etc.) is then made and the Enterprise Control Problem is posed as a top-down and holistic mathematical optimization problem (Chapter 3). Original models and methods of contract theory (Chapter 4), technology management (Chapter 5), human behavior and human capital (Chapter 6), complex activity and resource planning (Chapter 7) are developed to solve the problem. Structural, processes and mathematical models constitute Optimal Enterprise Control Framework (Chapter 8) that provides a practical solution to the Enterprise Control Problem. The book will be a valuable resource for Postgraduate and Doctoral students, Postdoctoral researchers, Professors with the research interests in the fields of science of: · Fundamental Complex Systems study, Complex Systems Engineering, Enterprise Systems Engineering. · Applications of Operations Research, Optimization, Probability and Stochastic processes to Management Science, Economics and Business. · Theory of the Firm. · Business and Management – general, strategy/leadership, organization management, operations management, management information systems. · Theory of business processes, business processes improvement and reengineering.