This document provides an introduction to organizational development (OD). It defines OD as a planned, organization-wide effort to increase effectiveness through interventions using behavioral science knowledge. The document outlines four approaches to OD: laboratory training, survey research and feedback, action research, and sociotechnical. It also discusses the underlying values and assumptions of OD, including that people strive for growth, groups influence behavior, and solutions consider the whole system. OD aims to improve organizations through collaborative management of culture.