Efficacy studies, like this study, are just the first step in establishing an evidencebased clinical intervention. Though the social communication subscale yielded significant results in this study, other “impact” [Ozonoff and Miller 1995] measures, including the total score and other subscales of the SRS as well as the parent skills ratings did not yield significant pre-/post- intervention changes. This is a common problem of efficacy studies and could be due to the short length of the intervention program, the small number of participants, or inappropriate and/or insensitive measures. In later phases of developing an intervention, these impact measures become more critical.