The purpose of this study was to test the efficacy of a comprehensive program model originally developed by the National Professional Development Center on Autism Spectrum Disorder (NPDC). Sixty elementary schools with 486 participants were randomly assigned to an NPDC and services as usual condition (SAU). Significantly greater changes in program quality occurred in the inclusive NPDC programs as compared with the SAU schools. Teachers in NPDC schools reported using more evidence-based practices (EBPs) and implemented EBPs with significantly greater fidelity than teachers in SAU schools. Autistic students in NPDC schools had significantly higher total attainment of educational goals than students in SAU schools, and the two groups made equivalent progress on standardized assessment outcomes across the school year. [This is the online first version of an article published in "Journal of Autism and Developmental Disorders."]