Autistic individuals are widely exposed to socially adverse events, such as social exclusion, bullying, and trauma. The social defeat hypothesis of schizophrenia predicts that these socially defeating experiences increase striatal dopaminergic functioning and thereby increase the risk of psychosis in autistic individuals. This thesis explores the associations between autism, social defeat, striatal dopamine, and psychosis. The research found that (a) autistic individuals are at an increased risk of psychotic disorder; (b) children with autistic traits are more likely to report psychotic experiences in young adulthood, and this is related to experiences of trauma in childhood; (c) striatal dopamine is not increased in autistic adults. These findings highlight the need for improved detection and treatment of psychosis in autistic individuals, and once again show the necessity of improving the social circumstances in which autistic individuals have to live.