Researchers at Stanford University are currently recruiting children with autism spectrum disorder to identify MRI-based markers of response to treatment with Pivotal Response Treatment (PRT) targeting language abilities. Children with autism spectrum disorder between the ages of 2 and 4 years 11 months are invited to participate. This study involves up to a 5 month time commitment. The participant must be willing to complete cognitive and behavioral assessments (such as IQ and language testing) and be able to either sleep (young children) or lie still in the scanner during an MRI. After a successful MRI, the participant will be randomized into the PRT trial or DTG (Delayed Treatment Group). PRT will consist of 16 weekly, 60-90 minute sessions of parent training in PRT over a 16 week time period. DTG will consist of your child’s treatments as usual in the community and measurements and questionnaires will need to be filled out on three study visits over the course of the 16 weeks. After completion of the DTG, the participant will be offered PRT parent training sessions similar to the PRT group.