Positive psychology is the study of the conditions and processes that contribute to the flourishing or optimal functioning of people, groups, and institutions. In this brief introduction, the authors give examples of current work in positive psychology and try to explain why the positive psychology movement has grown so quickly in just 5 years. They suggest that it filled a need: It guided researchers to understudied phenomena. The authors close by addressing some criticisms and shortcomings of positive psychology, such as (...) the relative lack of progress in studying positive institutions. (shrink)