Abstract
Recent research has revealed informative patterns about health, mental health, self-help skills, autism symptoms, and social skills during the transition to adulthood for autistic individuals. This study expands on these findings by examining how positive affect (e.g. excited) changes from age 15 to 30 years using a group of individuals first referred for autism at an early age. We also examined the agreement between caregiver-report and self-report on positive affect. We found different patterns of stability and change in positive affect across the transition to adulthood that related to differences in autism severity, cognitive abilities, self-help skills, as well as social and work participation in adulthood. The agreement between caregiver-report and self-report was strong in adolescence but became much weaker after the individuals were 23 years. These results have implications for how we measure happiness, positive emotions, or other internal experiences of autistic individuals.