Similarity in the experience of state affect is a common phenomenon for work team members and has been shown to have important consequences on team behavior and performance. We provide a comprehensive overview of the current state of research on group affective tone, including the development of group affective tone through affective convergence mechanisms, the conceptualization and operationalization of group affective tone, and the theoretical and practical consequences of positive and negative affective tones for group behavior and group performance. Finally, we highlight some emerging research directions that may provide promising avenues for future understanding of the complexity inherent in the formation and influence of state group affect.