In recent years, design has grown in importance for economic and technical development projects. This increase is in turn associated with very topical social issues.Yet, how can this dimension of design, i.e. "social design", be researched and made visible? This was the question that was tackled by the authors of this book to shed light on the specific rationalities of the processes and methods of design. Based on eight selected projects of applied design at the Zurich University of the Arts, from the areas of Industrial design, Interaction design and Game design, various networks of heterogeneous actors are described and discussed from various academic perspectives. The investigated design productions represent an intrinsic logic than can neither be limited to standardized sets of methods within the discipline nor to established methods outside it. At the same time, decoding the complexity of singular design processes contributes to the advancement of the formulation of design theory.