OBJECTIVE: Publicly funded mental health services play an important role in caring for children with mental health needs, including children with autism spectrum disorder (ASD). This study assessed the associations between individual family- and neighborhood-level sociodemographic factors and baseline family functioning and long-term outcomes when community therapists were trained to deliver An Individualized Mental Health Intervention for ASD (AIM HI). METHOD: Participants included 144 children with ASD (ages 5 to 13 years; 58.3% Latinx) and their caregivers whose therapists received AIM HI training within a cluster-randomized effectiveness-implementation trial in publicly funded mental health services. Sociodemographic strain (e.g., low income, less education, single-parent status, minoritized status) was coded at the individual family and neighborhood level, and caregivers rated caregiver strain at baseline. Child interfering behaviors and caregiver sense of competence were assessed at baseline and 6-, 12- and 18-months after baseline. RESULTS: Higher caregiver strain was associated with higher intensity of child behaviors (B = 5.17, p < .001) and lower caregiver sense of competence (B = -6.59, p < 001) at baseline. Child and caregiver outcomes improved over time. Higher caregiver strain (B = 1.50, p < .001) and lower family sociodemographic strain (B = -0.58, p < .01) were associated with less improvements in child behaviors. Lower caregiver strain (B = -2.08, p < .001) and lower neighborhood sociodemographic strain (B = -0.51, p < .01) were associated with greater improvements in caregiver sense of competence. CONCLUSIONS: Findings corroborate the importance of considering both family and neighborhood context in the community delivery of child-focused EBIs. TRIAL REGISTRATION: Clinical Trials NCT02416323.