The present study examines the impact of oxytocin (OXT) and Pivotal Response Treatment (PRT) on the development of language, social, and play skills in young children with Autism Spectrum Disorder (ASD). The purpose of this study is to examine the impact of OXT as an enhancer of response to PRT. Participants will be randomly assigned to either an intranasal OXT group or a placebo group. Neither the research team nor the participants will know or choose which group the participant is assigned to. Children in both groups will participate in a 16-week trial of PRT. The trial will test the hypothesis that children with lower levels of activity in and functional connectivity among certain PRT-response brain regions will benefit more from the administration of OXT vs. placebo as an enhancer to a 16-week trial of PRT.