Mental major illness, including psychotic disorders and mood disorders, has been linked to early prenatal/childhood factors and subsequent behavioral health concerns. For example, Watson et al. (1999) found that maternal illness and extreme stress during pregnancy disrupts fetal brain development, increasing the likelihood of depression or schizophrenia in later life. Research has also shown a dose-response effect between the number of adverse childhood experiences (ACEs) and mental health outcomes, with increasing ACEs linked to more severe mental health problems and suicide attempts (Merrick et al., 2017). Persons with major mental illness, like schizophrenia or bipolar disorder, are also at increased risk of suicidal and self-harm behaviors (Happell et al., 2012; Morden et al., 2009). These individuals also demonstrate a higher rate of substance use (Linszen et al., 1995) that often contributes to poor medical health (Dixon et al., 2000; Jeste et al., 1996). The current study sought to differentiate adolescents with and without major mental illness (i.e., psychotic or mood disorders) by investigating a sample of youth who were in a residential treatment facility for sexually abusive behaviors (N = 296). Data related to participants’ prenatal/birth concerns, ACE scores, history of suicide attempts and self-harm, and use of alcohol, tobacco, marijuana, and inhalants were gathered from archival records. Results indicated that there were a number of adolescents diagnosed with a psychotic disorder (n = 33) or mood disorder (n = 189). Two separate logistic regressions assisted with differentiating adolescents with and without psychotic or mood disorders using the specified predictors. A significant model (χ2 = 94.910, Nagelkerke’s R2 = 0.412, p < 0.001) correctly classified 76.4% of participants with a mood disorder. Adolescents with a mood disorder were 4 times as likely to have had prenatal or birth concerns (OR: 4.404, p < 0.001), and were significantly more likely to have higher ACE scores (OR: 1.148, p =.024). Further, those with a mood disorder were 2.5 times as likely to have self-harmed (OR: 2.673, p=.009), and approximately 23 times more likely to have attempted suicide (OR: 22.858, p=.003). Another significant model (χ2 = 29.842, Nagelkerke’s R2 = 0.210, p < 0.001) correctly classified 88.3% of participants with a psychotic disorder. Adolescents with a psychotic disorder diagnosis were significantly more likely to have higher ACE scores (OR: 1.237, p =.020), and were 4 times as likely to have a self-harm history (OR: 4.474, p=.005) compared to those without a psychotic disorder. Results indicate that prenatal/birth concerns appear to be a significant factor for those who are diagnosed with a mood disorder, but not with a psychotic disorder. Also, those with mood disorders, but not psychotic disorders, were more likely to have attempted suicide. Adolescents with either a mood or psychotic disorder both tended to self-harm and have experienced more ACEs. Interestingly, substance use was not higher among adolescents with mood or psychotic disorders, despite predictions and previous research findings.