Mother-child relationships characterized by dyadic synchrony, a mutually responsive and interconnected interaction style, have been consistently linked to children's psychosocial adjustment in early childhood, but it is unclear whether such interaction patterns remain conducive to positive outcomes in early adolescence. The aim of the present investigation was to examine mother-child synchrony and its link to early adolescents' self-esteem and prosocial behavior. Data were collected from 268 early adolescents and their mothers from both European American and African American families. Four components of dyadic synchrony were assessed during a structured mother-child interaction session. In addition, assessments of early adolescents' self-esteem and prosocial behavior were conducted approximately one year later. Results indicated that mother-child shared positive affect and conversational equality were highly intercorrelated components of dyadic synchrony. Moreover, early adolescents from dyads with high levels of dyadic synchrony and conversational equality had higher self-esteem. Early adolescents from dyads with high levels of shared positive affect were more prosocial with peers. Although the patterns of association were similar for African American and European American preadolescents, ethnicity did interact with certain components of synchrony in predicting early adolescents' self-esteem and prosocial behavior. (Contains 3 tables.)