This study examined differences in the rates of psychiatric-related emergency department visits among adolescents with autism spectrum disorder, adolescents with attention deficit hyperactivity disorder, and adolescents without autism spectrum disorder or attention deficit hyperactivity disorder. Additional outcomes included emergency department recidivism, probability of psychiatric hospitalization after the emergency department visit, and receipt of outpatient mental health services before and after the emergency department visit. Data came from privately insured adolescents, aged 12-17 years, with autism spectrum disorder (N = 46,323), attention deficit hyperactivity disorder (N = 408,066), and neither diagnosis (N = 2,330,332), enrolled in the 2010-2013 MarketScan Commercial Claims Database. Adolescents with autism spectrum disorder had an increased rate of psychiatric emergency department visits compared to adolescents with attention deficit hyperactivity disorder (IRR = 2.0, 95% confidence interval: 1.9, 2.1) and adolescents with neither diagnosis (IRR = 9.9, 95% confidence interval: 9.4, 10.4). Compared to the other groups, adolescents with autism spectrum disorder also had an increased probability of emergency department recidivism, psychiatric hospitalization after the emergency department visit, and receipt of outpatient care before and after the visit (all p < 0.001). Further research is required to understand whether these findings extend to youth with other neurodevelopmental disorders, particularly those who are publicly insured.