This document summarizes the development of the human relations movement from the 1920s to the 1940s. It began with empirical research on group dynamics and interactions that challenged views of isolated individuals in organizations. Notable researchers included Follett, Lindeman, Moreno and Lewin who developed new techniques like sociometry and field theory to study groups. Their work influenced later studies of social systems and organizational theory. In the 1930s-1940s, human relations research expanded and many new academic centers and programs were established to study work motivation and developing participative approaches to management through techniques like role playing and sensitivity training.