The document summarizes the history and development of Organization Development (OD) through four main trunks or stems: (1) laboratory training stem including T-groups and workshops, (2) survey research and feedback stem involving techniques like surveys, (3) action research stem being collaborative client-consultant inquiry, and (4) socio-technical and socio-clinical stem examining work groups and tasks. It then discusses areas of increased focus in second generation OD like organizational transformation, culture, learning organizations, teams, and visioning.