Environmental sustainability creates both tremendous business opportunities and formidable threats to established companies across virtually all industry sectors. Yet many companies tackle the issue in a superficial or passive way, rather than considering fundamental changes to their existing business models. By ignoring the opportunities of Green Business Model Transformations, companies exclude themselves from a large variety of potential means to create economic value. In addition to ordinary product and process innovations, they can change the rules of the game within an industry towards environmental sustainability.Green Business Model Transformations, however, are challenging ventures: New, green business models with all their uncertainties and inherent complex systemic characteristics are difficult to design, assess, and implement successfully, particularly in the context of established companies that often entail complex structures and considerable inertia. As a result, there is a great need for guidance in management practice. This publication addresses this need with a general approach to Managing Green Business Model Transformations that is based on a broad theoretical foundation, illustrated by many real-world examples from various industry sectors.