This study aims to examine the relationships between the mental health of parents whose children present with disruptive behavior problems and parents’ engagement in their children’s mental health treatment. Many studies have examined the impact of parents’ mental health and parent engagement on child treatment outcomes, and more studies are needed to understand the relationships between parent mental health and parent treatment engagement. As parent engagement has a positive impact on children’s treatment, the knowledge gained from this study can help to guide ways to increase parent engagement in children’s mental health treatment through addressing parent mental health issues. There were 18 therapists and 19 parent-child dyads that participated in the study from five publicly funded community mental health clinics. Participants were from a pilot intervention study that examined the use of a parent participation toolkit. Parents completed depression and anxiety measures (PHQ-8 & GAD-7); therapists completed the Hall Engagement Measure about parent participation and reported on session attendance; parents’ participation behaviors were also coded from video recordings of sessions. Multiple regression models were used to control for study condition, and examined the associations between the predictor variables of parent depression and anxiety and the three parent engagement dependent variables. Result showed that parent mental health predicted parent treatment engagement. The effect sizes indicated that parent mental health is associated with the therapist-reported Hall Engagement Measure and attendance, but not with the observational coding of parent participation behaviors in sessions. The findings give preliminary support for future studies to address parent mental health problems in children’s treatment to increase parent treatment engagement.