This follow-up study evaluates the behavioral, language, and social outcomes in a population of autistic patients initially examined in childhood. We evaluated 102 (63%) of the 163 eligible subjects, including 54 adolescents (12-17 years of age) and 45 adults (> or = 18 years of age). Three patients had died in the interim. Behavior difficulties continued to be a problem in 69% of adolescents and adults. Thirty-five percent of adolescents and 49% of adults engaged in self-injurious behavior, and slightly more than 50% of adolescents and adults exhibited some stereotypic behaviors. Over 90% of both adolescents and adults had persisting social deficits. Language improved with age, although only 35% achieved normal or near-normal fluency. Comprehension also improved, although only 29% of subjects had achieved normal or near-normal comprehension of oral language. At the time of last follow-up, 28% of all patients and 53% of adults were living in residential placement. Only 11% of adults were employed on the open market, all in menial jobs; an additional 16% were employed in sheltered workshops. The social, behavioral, and language deficits identified in early life in autistic children tend to persist into adolescence and young adulthood.