This book documents a paradigm shift, not only in the sciences but also in society. Everywhere in society systems are becoming networks. This implies not only a new understanding of social science but also of society and ourselves. The book describes the systems model based on Luhmann s theory of social systems and compares this to Latour s actor-network theory. It argues that present day society cannot be successfully modeled as a system and illustrates the transformation to a global network society by citing many examples from business, education, and healthcare. The authors argue that actor-network theory provides a more comprehensive account of these changes than systems theory. Based on actor-network theory, they propose a theory of the digital transformation that is ushering in the global network society. Although people in all areas talk about systems, adaptive behavior, evolution, complexity, and networks, few know where these concepts come from, and what they mean in the theories they belong to. This book is for all who are concerned with clarifying the often taken-for-granted assumptions and concepts that are implicitly or explicitly derived from systems theory and network theory. It offers an introduction to the work of Luhmann and Latour and a critical and constructive development of these important theories for the 21st century.