<p>Parenting interventions are a front-line treatment for children with attention-deficit/hyperactivity disorder (ADHD). However, many parents of children with ADHD have elevated ADHD or depressive symptoms, which may impede their ability to engage in and benefit from such interventions. This secondary data analysis examined associations between parent mental health, treatment engagement, and parenting-related treatment outcomes within a randomized trial of 172 families of children with ADHD. Families received either Parental Friendship Coaching (PFC; a behavioral parent training program) or Coping with ADHD through Relationships and Education (CARE; a parent psychoeducation and social support intervention); both were parenting interventions that aimed to support parents to improve children’s ADHD-related social impairments. Higher parent self-reported ADHD symptoms at baseline were associated with lower home practice completion in PFC, potentially greater perceived group social support in PFC, and higher attendance in CARE. In contrast, parent depressive symptoms were not associated with engagement in either intervention. Overall, higher parent ADHD or depressive symptoms demonstrated few associations with parenting behavior treatment outcomes at post-treatment or 8-month follow-up, and observed effects were both positive and negative in PFC and CARE. It is possible that accessibility-focused adaptations to PFC and CARE reduced the impact of higher parent mental health symptoms on poorer engagement and parenting treatment outcomes. Nevertheless, the generally low levels of ADHD and depressive symptoms in the sample limit the ability to detect possible stronger associations.</p>