Our objective was to predict change in maternal stress over the course of a randomized clinical trial comparing the efficacy of two interventions for Oppositional Defiant Disorder (ODD): Parent Management Training and Collaborative & Proactive Solutions. In a secondary analysis of data collected from this randomized clinical trial, we examined whether children’s self-reported positive relations with their parents impacted responsiveness to treatment, which in turn impacted maternal stress. One hundred thirty-four children and their parents (38.1% female, ages 7–14, M age = 9.51, SD = 1.77) were tracked across three time points: pre-treatment; one-week post-treatment; and six-month post-treatment. Hierarchical linear models tested change in children’s reports of positive relations with parents, clinician reports of ODD severity, and maternal reports of parenting stress. Models then tested multilevel mediation from positive relations with parents, through ODD severity, onto maternal stress. Hypothesized indirect effects were supported such that children’s reports of positive views toward parents uniquely predicted reductions in ODD severity over time, which in turn uniquely predicted reductions in maternal stress. Results highlight the promise of potential secondary benefits for parents following interventions for children with oppositional problems. Furthermore, results underscore the importance of the parent–child relationship as both a protective factor and as an additional target to complement interventions for child disruptive behaviors.