Pivotal Response Treatment Package for Young Children With Autism

Inclusion Criteria: * Diagnosis of Autism Spectrum Disorder (ASD) based on Autism Diagnostic Interview- Revised (ADI-R), Autism Diagnostic Observation Schedule (ADOS-2), and expert clinical opinion * Males and females in good medical health between 2.0 and 5.11 years * Ability 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: Standard score at least 1 Standard Deviation below average for expressive language ability * Stable treatment, speech therapy, school placement, psychotropic medication(s) or biomedical intervention(s) for at least 1 month prior to baseline measurements with no anticipated changes during study participation * No more than 60 minutes of individual 1:1 speech therapy per week * Availability of at least one parent who can consistently participate in parent training and research measures * Parents intend on continuing Pivotal Response Treatment Package (PRT-P) for a minimum of 12 weeks * Parents must be 18 years of age or older Exclusion Criteria: * Current or lifetime diagnosis of severe psychiatric disorder, such as bipolar disorder * Receiving in-home Applied Behavior Analysis (ABA) of 10 hours or more * A genetic abnormality, such as Fragile X * Presence of active medical problem, such as unstable seizure disorder or heart disease * Previous adequate PRT trial * Participants living more than 50 miles from Stanford University * At least one room of the house must be available to be dedicated to treatment during session times * There must be no serious health and safety risks present in the home environment * The research team has the right to refuse to perform sessions in-home even if the criteria above are met