This study aims to examine the associations between parental services efficacy to participate in mental health treatment for their child with disruptive behavior problems and both their actual participation and their child’s treatment outcomes. Parental services efficacy refers to how confident a parent is in their ability to effectively promote their child’s success in treatment. Parents' engagement in their child’s treatment is also considered an important part of treatment effectiveness. Many studies have examined the impact of parental service efficacy in children’s medical treatment, but not on mental health treatment outcomes. More studies are needed to understand the potential role of parental services efficacy in child mental health treatment. There were 19 therapists and 18 parent-child dyads who 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 reported on their services efficacy at baseline and follow-up. The engagement outcomes included therapist reports of attendance and parent engagement at follow-up as well as an observational measure of parents’ engagement behaviors in sessions. Children’s treatment outcomes were examined at baseline and follow-up, including parents’ reported perceptions of treatment effectiveness and frequency of disruptive behaviors. Regression models were used to control for study condition and ethnicity. Results indicated that parent services efficacy is not positively associated with engagement or treatment outcomes. One effect size was small but close to meaningful with an effect size of (f2=0.027). For most predictors effect size was almost nonexistent, which indicated a low likelihood of associations. Given the pilot nature of this study, future research may still be warranted to understand the potential role of parent services efficacy in parents’ treatment engagements and children’s treatment outcomes.