The proposed project will pilot the use of IGF-1 as a novel treatment for core symptoms of autism. We will use a double-blind, placebo-controlled crossover trial design in five children with autism to evaluate the impact of IGF-1 treatment on autism-specific impairments in socialization, language, and repetitive behaviors. We expect to provide evidence for the safety and feasibility of IGF-1 in ameliorating social withdrawal in children with Autistic Disorder. Further, we expect to demonstrate that IGF-1 is associated with improvement on secondary outcomes of social impairment, language delay, and repetitive behavior, as well as on functional outcomes of global severity.