This grant provides support for an NIH Autism Center of Excellence (ACE). The proposed study addresses gaps in knowledge of early intervention for infants at risk of autism spectrum disorder (ASD) by testing the efficacy of an early social communication intervention (Baby JASPER), which focused on joint attention, a core deficit in young children with ASD and an important area of concern for at-risk infants. A rigorous randomized controlled treatment design will be used to compare classroom-based Baby JASPER to a hospital-based early intervention program that focuses on early motor development, cognition, adaptive and social skills (Baby Standard). Primary outcome measures will focus on social-communication and language abilities of the infants with secondary measures of parent interactions and electrophysiological measures to examine biomarkers of change with treatment as well as predictors of social communication outcomes. An effective parent-mediated intervention with a focus on core deficits may result in better language and, ultimately, improved social outcomes for at-risk infants.