This study will determine the impact of early intervention on the communication and social development of toddlers with autism.

Autism is a condition that affects brain development, often leading to difficulties in social, emotional, and educational functioning. This study will determine whether early intervention can improve such functioning in toddlers with autism.

Each treatment session will last 6 months. Children with an autism spectrum disorder will be enrolled in one of two parallel classes and will receive one of two treatments 4 days a week for the duration of the session. Children in each class will receive the same amount and level of intervention, but with a different goal focus. Treatments will be school- and home-based; parents will receive instruction on administering the at-home part of the treatment. The intervention will include environmental engineering, developmental approaches, adaptations of traditional behavioral approaches, and contemporary behavioral approaches that apply principles of applied behavior analysis in more naturalistic teaching frameworks. A series of measures including scales, interviews, and observations will be used to assess the children at baseline, study completion, and 6 months after study completion. The children will be videotaped during the school-based intervention.

Inclusion Criteria:

• Diagnosis of autism spectrum disorder
• Parent or guardian willing to give informed consent for child's participation
• Developmental level above 9 months on the Visual Reception Scale of the Mullen Scales of Early Learning and on the Adaptive Behavior Composite of the Vineland Adaptive Behavior Scales
• English is primary language for child and family

Exclusion Criteria:

• Evidence of vision or hearing impairment
• Diagnosis of fragile X syndrome, Rett syndrome, tuberous sclerosis, neurofibromatosis, phenylketonuria, or congenital rubella
• History of severe birth trauma or traumatic brain injury
• Siblings with autism spectrum disorder