This study examined outcomes from the Systemic, Therapeutic, Assessment, Resources, and Treatment (START) program, a community-based tertiary care model for individuals with intellectual and developmental disabilities and mental health needs. The sample included 111 START service users and their family caregivers, who were receiving START Clinical Team services, located in the Northeast and Southwest regions of the United States. Results from the analyses found a significant 1-year pre-post improvement in caregiver service experiences and mental health symptoms of the service user. A significant decrease in psychiatric hospitalizations and emergency department visits was also found (all p < .01). These data suggest that START holds promise in improving outcomes, for both the caregiver and service user, while reducing dependence on costly and restrictive hospital-based services.