Groups exist for many reasons—some social (providing settings where we can satisfy our need to belong), some symbolic (contributing to our sense of identity), and some task related (e.g., making a decision, solving a problem, winning a sports competition). This entry deals with the latter reason—performing a group task—and considers some of the ways in which aspects of the group's task guide how the group and its members behave. This is particularly important because generalities about groups (e.g., “groups are better performers than individuals”) are all too often asserted as if they held true across any and every task that a group might confront. To the contrary, nearly any assertion about group behavior must take into account the nature of the group's task. With few ...