Kurt Lewin (1890 -1947) was a visionary psychologist and social scientist who used rigorous research methods to establish an approach to planned change that is both practical and reliable. He mentored and inspired most of the early professionals who came to identify themselves as practitioners of organization development (OD). He also fostered the emergence of the experiential learning method known as the T-group, which uniquely structures group dynamics into a laboratory for dramatic individual and team development. In the early days, most OD professionals learned much about themselves and about group dynamics through T-group experiences. Lewin’s methods, though little known, yield consistent business results such as increased performance and morale. His methods have the rare impact of not just changing behavior, but of changing the beliefs that underlie behavior. Sadly, most OD professionals today, business and organizational leaders, community organizers, and people in general, have never read any of Lewin’s actual writing beyond a quote or two. Indeed, some in the OD profession have rejected or distanced themselves from what they think Lewin taught, even though they and many others seem to know very little about his methods or history. Because Lewin was a prolific writer, one of the author's main goals is to organize his immense body of published work so that the reader can easily explore the source material and form their own opinions. Lewin held a doctorate in psychology and most of his publications are in psychological journals and books. This book is written from the perspective of an organization development practitioner. Although the focus is on planned change, in Lewin’s universal framework that includes individual change, and absolutely includes psychology. Essentially, this book is aimed at introducing Lewin in a new way, both simplified yet substantial enough to guide anyone who is trying to plan change, whether at the individual, group/team, organizational, or societal level. Lewin was not trying to create methods for OD professionals alone (or for social scientists as he regarded himself). In his interventions, he taught those how to do their own version of planned change. He believed social science might be the light that helps create a brighter future for humanity. The book transfers this knowledge to a broad audience, so that each reader can more successfully implement organizational and social change.