The current study follows two cohorts of fourth and fifth graders across 1 school year to better understand why some students change peer groups. The study focuses on popularity and intragroup social status. We examined whether differences between individuals' and group members' self-perceptions of popularity were related to changing peer groups. In addition, we investigated whether more peripheral group members were likely to leave their peer group. Results suggest that not only are peripheral group members and group members with dissimilar self-perceptions of popularity more likely to change groups, but they have more similar self-perceptions of popularity in their new groups. By employing a novel method of measuring within-group homophily, the current study expands the sparse literature on why individuals might change group membership. (Contains 6 tables.)