This is the first comprehensive overview of the development of the field of Organizational Behavior. It belongs on the shelf of every scholar and student in the discipline. Part I covers the foundations of the scientific method, theory development, and the accrual of scientific knowledge in the field. Part II introduces the ideas of pioneers whose work pre-dates the emergence of Organizational Behavior. Part III considers the actual emergence of OB as we know it today, with an analysis of the environmental forces that impinged upon it (such as the recruiting of social scientists into business schools). Part IV presents an assessment of the current state of the art in OB research, with an original assessment of the importance, validity, and practical usefulness of 73 core theories in OB. Finally, Part V sets forth a vision for the future identity and growth of Organizational Behavior research, theory, and practice.