Background <p>Depression is prevalent among autistic youth and has significant negative impacts on quality of life and daily functioning; nonetheless, there has been limited intervention research addressing depression for this group.</p> Methods <p>This mixed methods study investigated the acceptability and appropriateness of a novel, behavior-based approach for treatment of depression symptoms in autistic adolescents without intellectual disability (i.e., Behavioral Activation for Autistic Adolescents, BA-A), as part of a single-arm/open trial with 15 autistic youth (11–16&#xa0;years of age). BA-A is an individually delivered, 12-session manualized intervention. At the BA-A post-treatment assessment visit, autistic adolescents and their caregivers completed semi-structured qualitative interviews and validated quantitative measures of their satisfaction with BA-A.</p> Results <p>Autistic youth and their caregivers reported satisfaction with BA-A on validated and commonly utilized quantitative measures of intervention acceptability and appropriateness. Autistic adolescents and caregivers similarly indicated that BA-A is acceptable and appropriate in qualitative interviews as evidenced by favorably describing the intervention content/materials, structure, and flexibility of the implementation.</p> Conclusions <p>Quantitative and qualitative findings provide converging evidence that BA-A is acceptable to autistic adolescents with depression symptoms and their caregivers, as well as appropriate for this population.</p>