The purpose of this study was to investigate comorbid psychiatric disorders and psychotropic medication use among adults with autism spectrum disorder (ASD) ascertained as children during a 1980’s statewide Utah autism prevalence study (n = 129). Seventy-three individuals (56.6 %) met criteria for a current psychiatric disorder; 89 participants (69.0 %) met lifetime criteria for a psychiatric disorder. Caregivers reported a psychiatric diagnosis in 44 participants (34.1 %). Anxiety disorder had the highest current and lifetime prevalence (39.5 and 52.7 %, respectively). Participants with intellectual disability (n = 94, 72.8 %) were significantly less likely to have community-based diagnoses of anxiety (χ² = 5.37, p = 0.02) or depression (χ² = 13.18, p < 0.001) reported by caregivers. Seventy-six participants (58.9 %) were taking ≥1 psychotropic medication. Comorbid psychiatric disorders occur frequently in adults with ASD, though identifying these disorders poses a challenge in community settings. A greater understanding of the presentation of these conditions within this population will increase assessment validity and the potential for efficacious intervention.