Many organizational goals are simply too big and too complex for a single person to execute. This is one of the reasons that teams are an important component of what gets done day to day around the world. Not surprisingly, then, teams are also, in large part, how work is organized and gets done within organizations. Because of this, I-O psychologists need to understand teams in the workplace. This chapter addresses what teams are and what they are not; the team development process; ways to maximize process gains and minimize process losses; features of effective teams; team decision-making; key legal and global issues surrounding work teams; and the current issues and research around work teams.