Autism spectrum disorder (ASD) is a very heterogeneous disorder with limited empirically validated behavioral and biological interventions. The goal of this pilot investigation is to apply a biologically-based approach to identify predictors of treatment response in children with ASD who are receiving Pivotal Response Treatment (PRT), an evidence-based behavioral intervention. Specifically, the investigators propose to identify neuroimaging biomarkers of treatment response to a PRT program (PRT-P) targeting language deficits in young children with ASD who will be randomized to either PRT-P or to a delayed treatment group (DTG).

Inclusion Criteria:

• Diagnosis of Autism Spectrum Spectrum Disorder (ASD) based on clinical interview and Diagnostic and Statistical Manual, 5th edition (DSM-5) and confirmed using the Autism Diagnostic Interview Revised (ADI-R) and the Autism Diagnostic Observation Schedule (ADOS) and/or Brief Observation of Symptoms of Autism (BOSA) and/or Childhood Autism Rating Scale- Second Edition (CARS-2).
• Outpatients between 2.0 and 4.11 years of age of either gender,
• Children of all cognitive levels will be included as long as they are able to participate in the testing procedures to the extent that valid standard scores can be obtained
• Language delay as measured by the Preschool Language Scale, 5th Edition (PLS-5) [at least 1 standard deviation behind for children age 2 and 3 years; and 2 standard deviations behind for children age 4],
• Stable psychotropic medication(s) or biomedical intervention(s) for at least 1 month prior to baseline measurements with no anticipated changes during study participation,
• Stable treatment [Applied Behavior Analysis (ABA), Floortime, or other interventions], speech therapy, and school placement for at least 1 month prior to baseline measurements with no expected changes during study participation,
• No more than 60 minutes of 1:1 speech therapy per week,
• The child's exposure to the English language must be sufficient that administration of standardized tests in English is appropriate for measuring progress,
• The availability of at least one parent who can consistently participate in the training sessions and related activities, and
• Successful completion of baseline brain scan.

Exclusion Criteria:

• Current or life-time diagnosis of severe psychiatric disorder (e.g., bipolar disorder),
• Genetic abnormality (e.g., Fragile X)
• Presence of active medical problem (e.g., unstable seizure disorder),
• Receiving more than 15 hours of in home 1:1 Applied Behavior Analysis (ABA) per week
• Magnetic Resonance (MR) contraindication (e.g., the presence of ferrous metal), or
• Previous adequate Pivotal Response Treatment (PRT) trial.

We will submit de-identified clinical data to the NIMH Data Archive (NDA) data repository.