Children with autism spectrum disorder (ASD) benefit from parent involvement in their therapy, and there is evidence that this involvement may improve parent functioning as well. We examined changes in parent mental health, parenting, and expressed emotion, following participation in a randomized controlled trial of cognitive behavior therapy for 57 children with ASD. Post-intervention, improvements occurred in the treatment group in parent depression and emotion regulation, compared to waitlisted parents. Treatment effects also occurred across all parents in depression, emotion regulation, perceptions of their children and mindful parenting. Though preliminary, these results have implications for intervention development and evaluation by focusing on parent outcomes in child treatment.