Parents play an essential role in the transition to adulthood for autistic youth, yet often feel they do not have adequate training and resources. To evaluate data on the preliminary efficacy of and collect participant feedback about the Maximizing Adolescent Post-Secondary Success (MAPSS) intervention. Single-group, pretest-posttest pilot study. Clinic. Twenty-two families of autistic youth (ages 13-19 yr, 72.7% male). MAPSS is a group intervention for parent-youth dyads that is designed to guide parents in facilitating the development of independent skills for adulthood. Outcomes and Measures: Measures included the Transition Preparation Activities Measure (T-PAM), Family Empowerment Scale (FES), 10-item Perceived Stress Scale (PSS-10), Adulthood Expectations Questionnaire (AEQ), Adaptive Behavior Assessment System-Third Edition (ABAS-3), and a study-specific participant feedback survey. Frequency of transition preparation activities (T-PAM) significantly increased from before to after the intervention, and although the frequency of preparation activities decreased by 1-mo follow-up, it remained significantly higher than at baseline. Parent self-efficacy (FES), parent expectations (AEQ), and parent sense of control over outcomes (AEQ) also significantly increased from preintervention to follow-up; however, parent coping (PSS-10) was unchanged. Youth self-care skills (ABAS-3) demonstrated improvements 6 mo after the completion of the intervention, although other areas of adaptive behavior did not significantly change. Feedback from parents suggested they had positive experiences and felt the intervention was beneficial. Our data suggest that the MAPSS intervention is an appropriate candidate for larger, controlled clinical trials. What This Article Adds: With additional evidence, this intervention can offer guidelines for occupational therapists to work with autistic youth and their parents to prepare for adulthood.