The importance of models in support of managers is still widely underestimated. An argument frequently heard imputes that change and complexity in our time are so ubiquitous and mighty that models do not provide adequate orientation. We argue the contrary: The more that people in organizations are confronting complexity, the more will their performance depend on the quality of the models underlying their activity: More than ever do they need orientation, and that is what good models can provide.In this e-book we set model-based management in the context of general management with an emphasis on the systemic, generalist, integrative stance, while obtaining views of different functions or disciplines from the specialist. With Hans Ulrich we conceive of management as the design, governance and development of productive Social Systems. Our approach is to take a systems perspective on the state-of-the-art, eliciting insights that may be relevant for any kind of organization, private or public, profit or non-profit, large or small, regardless of the kind of business they are in.