In middle childhood, childrens affiliation-based groups, or cliques, provide an important context for their social development. The overall goal of the study, which consists of two manuscripts, was to examine the contribution of clique characteristics to childrens social and emotional adjustment. The first manuscript presented different types of cliques based on aggregated behavioral characteristics of clique members. It was also found that average levels of clique members social status and childrens social adjustment outcomes differ across types of cliques. In the second study, the interaction between clique type to which a child belongs and perceived cohesion of the clique on his or her social adjustment was examined. The results indicated that the degree to which clique members are perceived to be similar (i.e., perceived cohesion) moderates the link between type of clique and childrens social adjustment. The thesis concludes with a summary of findings and suggestions of future directions.