This chapter addresses the social effects of emotions in groups. The chapter starts with a brief discussion of theorizing on the social functionality of emotions in groups. Against that background, I discuss classic work on various types of affective processes in groups, including emotional contagion, affective convergence, and affective divergence, which will be followed by a review of research on the consequences of group-level affective states such as group affective tone and affective diversity for group functioning. I will then proceed to review more recent work on inferential processes that may be triggered by emotional expressions in groups and their downstream consequences for group processes and outcomes. The chapter ends with some emerging conclusions regarding the contingencies that govern the social effects of emotions in groups.