Investigating social participation of young adults with an autism spectrum disorder (ASD) is important given the increasing number of youth aging into young adulthood. Social participation is an indicator of life quality and overall functioning. Using data from the National Longitudinal Transition Study 2, we examined rates of participation in social activities among young adults who received special education services for autism (ASD group), compared to young adults who received special education for intellectual disability, emotional/behavioral disability, or a learning disability. Young adults with an ASD were significantly more likely to never see friends, never get called by friends, never be invited to activities, and be socially isolated. Among those with an ASD, lower conversation ability, lower functional skills, and living with a parent were predictors of less social participation.