This study examines whether aggression and prosocial behavior shape changes in
perceptions of friendship quality within stable reciprocal best friend dyads. A
longitudinal Actor-Partner Interdependence Model was used to investigate whether
individual characteristics predict changes 6 to 12 weeks later in perceptions of
relationship support and negativity. The sample included 76 same-sex dyads drawn from
classrooms in grades 4 (M = 9.48 years) through 6 (M= 11.43 years) in two public
schools in the United States.