Patients with autism spectrum disorder and/or intellectual disability (ASD/ID) face unique health care challenges. In addition to hospital experiences characterized by fear and insufficient staff training, these patients have 1.5-times longer lengths of stay (LOS) than patients without ASD/ID, and 3.4% of patients with ASD/ID have prolonged LOS (i.e., ≥30 days). Little research exists on factors related to prolonged LOS of patients with ASD/ID, hindering efforts to develop and implement evidence-based practices to improve care and reduce prolonged LOS. The purpose of the current study was to describe factors related to prolonged LOS of adult patients with ASD/ID in acute care settings using a retrospective chart review of 10 patients discharged from one academic medical center. Findings indicate that health care institutions should evaluate performance with this patient population and identify evidence-based strategies to provide a safe environment for care and reduce LOS that is due to non-health care needs.