Organizational and systems change, a primary focus for many consulting psychologists and other professional consultants, requires a subtle knowledge of human organizations, cultures, and societies. This text provides conceptual and operational descriptions of the major approaches to the field of organizational and systems change (O/SC). It describes a variety of strategies and principles involved in O/SC, including general systems theory, chaos and complexity theory, organizational development and change management, organizational and personal learning, psychodynamics and covert processes, and emerging areas of interest including the integration of positive psychology, appreciative inquiry, behavioral theory, and neuropsychology into the practice of O/SC. This book offers a broad and comprehensive treatment of the research behind and challenges involved in motivating and effecting large-scale human systems change. While the authors discuss interventions at the individual, group, and organizational/systems level, the outcome of these efforts is focused upon organization and system success, improvement, and survival. The authors provide a thorough overview of theories and strategic approaches in this area, how they developed, the evidence base for their use in practice, practical and effective mental models, examples of how the strategies and models can be applied, and references that will provide the reader with a deeper understanding of the concepts discussed. This book is an invaluable reference resource for anyone wanting to enter or progress in the field of organizational consulting.