We examined whether mother-child discrepancies in perceived child behavior problems relate to dysfunctional interactions between mother and child and stress in the mother. Participants included 239 children (6–16 years old; 58 girls, 181 boys) referred for oppositional, aggressive, and antisocial behavior, and their mothers. Mother-child discrepancies in perceived child behavior problems were related to mother-child conflict. Moreover, maternal stress mediated this relationship. The findings suggest that discrepancies among mother and child evaluations of child functioning are not merely reflections of different perspectives or artifacts of the assessment process, but can form components of conceptual models that can be developed and tested to examine the interrelations among critical domains of child, parent, and family functioning.