Purpose: Family Peer Advocates (FPA) are used in healthcare broadly to facilitate engagement and address disparities in care. We previously reported on the benefit of FPAs in the care of autistic children on caregiver stress. Caregivers of autistic children report significant levels of caregiver stress, in particular when associated with co-occurring conditions, such as Attention Deficit/Hyperactivity Disorder (ADHD), which is associated with significant burden and rarely addressed by traditional systems of care. The present study employed a randomized, wait-list controlled design over six months to further evaluate the utility FPAs on the care of autistic children on caregiver stress, family quality of life and treatment utilization in underserved LatinX and Black autistic individuals and their caregivers. Our central hypothesis is that FPAs will be particularly beneficial to autistic participants with co-occurring ADHD. Methods: Participants were randomly assigned to the intervention group (FPA, n = 24) or the control group (treatment as usual, n = 24). Participants assigned to the intervention group completed 12 one-to-one contacts (four in-person, eight remote) with their assigned FPA over a six-month period. All FPAs were certified in New York State and trained to deliver the Parent Empowerment Program. Primary outcome measures were caregiver stress and family quality of life. Secondary outcomes included child behavioral outcomes (i.e., irritability and hyperactivity), home behavioral compliance and service utilization. Variables were measured at baseline, month three and month six. Results: We observed clinically significant improvements in the intervention group on caregiver strain, family quality of life, and disruptive behaviors for autistic participants with co-occurring ADHD, while family treatment satisfaction improved irrespective of co-occurring ADHD. Conclusion: We propose that the FPA model is especially beneficial for caregivers of autistic children with co-occurring ADHD and/or those with a higher incidence of externalizing behaviors.