This chapter introduces organizational behavior and its key concepts. It discusses how OB focuses on improving organizational effectiveness by studying the impact of individuals, groups, and structure on workplace behavior. The chapter outlines the managerial functions and roles, and explains OB's multi-level model of analysis including individual, group, and organizational factors that influence important dependent variables like job satisfaction and productivity. It also discusses the behavioral science disciplines that contribute to the field of OB and how both systematic study and intuition can inform management practice.