here is consensus that PRT increases communication, interpersonal, and play skills when applied to children with autism aged between 3 and 9 years (Gillett & LeBlanc, 2007; Harper, Symon & Frea, 2008; Koegel, Carter & Koegel 2003). This conclusion is given added weight by a large study of 158 families of children with autism conducted by Baker-Ericzén, Stahmer, and Burns (2007). All children showed significant improvements on adaptive functioning on the Vineland Adaptive Behaviour Scales (Sparrow, Balla, & Cicchetti, 1984). Children younger than 3 years showed the least impairment at the beginning of the intervention and the most improvement at the end.