This study examined the relation between mothers' positive and negative interaction behaviors during mother-child interactions and the emotion regulation (ER) and depressive symptoms of their adolescent offspring. Event-planning (EPI) and problem-solving interactions (PSI) were observed in 163 mother-adolescent dyads, and adolescents also provided a self-report of ER responses and depressive symptoms. Sequential analyses of mother-adolescent behaviors during the interaction tasks indicated that adolescents with more depressive symptoms were more likely to reciprocate their mothers' negative affective behaviors. Adolescents whose mothers displayed less positivity and more negativity (i.e., less frequent positive and more frequent negative behaviors) during the EPI displayed more emotionally dysregulated behaviors in the PSI and reported more frequent maladaptive ER responses. Adolescents whose mothers behaved negatively toward them more frequently during mother-adolescent interactions also reported more depressive symptoms. The frequency with which adolescents engage in maladaptive ER responses mediated the association between maternal negativity and adolescents' concurrent depressive symptoms.