The aim of this study was to examine the responsiveness of the Psychoeducational Profile-third edition (PEP-3) in children with Autism Spectrum Disorders (ASD). We investigated the responsiveness in terms of three types of scores (i.e., raw scores, developmental ages, and percentile ranks) of the subtests and composites of the PEP-3 and three methods of analysis were used: effect size, standardized response mean, and paired t test. The findings generally support the use of the PEP-3 as an outcome measure. We suggest using the raw scores and developmental ages of the PEP-3 when evaluating program effectiveness and developmental changes for children with ASD. (Contains 3 tables.)