This book explores the basic concept of agency and develops it further in psychology, using it to better understand and explain psychological processes and behavior. More importantly, this book seeks to put an emphasis on the role of agency in four distinct settings: history of psychology, neuroscience, psychology of religion, and socio-cultural theories of co-agency. In Volume 12 of the Annals of Theoretical Psychology, the contributors will explore a number of new ways to look at agency in psychology. This volume seeks to develop a systematic theory of axioms for agency. It describes implications for research and practice that are founded on an understanding of the person as an actor in the world. This book also has implications for research and practice across psychology’s sub-fields, uniting the discipline through an agentic view of the person.