This study investigates friendship selection and influence processes in relation to popularity, aggression, and prosociality among 613 fifth graders in 26 classrooms within one academic year. Results showed that youth tended to select their friends based on similarity in popularity more than similarity in aggression or prosociality. Aggressive youths tended to select prosocial peers as friends given similarity in popularity, but prosocial youths did not disproportionately nominate aggressive peers. Socialization within friendships was evident for aggressive and prosocial behavior and popularity. Discussion considers the importance of social status as a grouping mechanism in peer social ecologies, and as a malleable factor that can impact student adjustment.