Parents are an integral component of treatment for individuals with autism spectrum disorders (ASD) as they provide continuity, maintenance, and generalization of learned skills. It is crucial that parents adhere to prescribed recommendations to optimize treatment effectiveness. However, it remains unclear how individual or familial contextual factors influence parental adherence. Two hundred and two caregivers of individuals with ASD completed online questionnaires. Questionnaires screened for accuracy of diagnosis, measured current ASD symptoms, adaptive functioning, and parental adherence to treatment recommendations. These data showed adaptive functioning was predictive of parent adherence to medical treatment recommendations over and above what was accounted for by parent-reported diagnoses. Contrary to our predictions, we did not find a relationship between ASD symptom severity or our predicted familial and contextual factors and adherence. When prescribing treatment recommendations, professionals need to be cognizant of how individual and familial contextual factors influence parental adherence.