The present study examined the content of applied behavior analytic therapy (ABA therapy) on skill acquisition and intelligence test scores of twenty-eight children with autism and related disabilities. Using a randomized controlled trial, we compared (a) traditional ABA consisting of verbal behavior techniques developed by Skinner (Verbal behavior, Appleton-Century-Crofts, New York, 1957), (b) comprehensive ABA which added techniques post-Skinner's theory of language, and (c) waitlist control. Results obtained indicated that even though skill acquisition improved equally across both intervention groups compared to the control, highest intelligence score changes were shown for participants in the comprehensive ABA group (F: 2, 24 = 9.198, p = 0.001). With increasing emphasis on client outcomes, the present data suggest that when hours of intervention are kept constant, ABA service providers may be at an advantage by incorporating techniques that are typically considered beyond the traditional ABA ideas of Skinner's account of language development.