Optimism and loneliness, which reflect the expected inverse associations with excess morbidity and mortality, are theoretically and empirically associated with early adversities and offer potential avenues for clinical support. The current study first estimates latent classes of adverse childhood experiences and, second, assesses the role of these experiences on later reports of optimism and loneliness in late adolescence and emerging adulthood, and the role of emotional regulation and common mental disorders. Surveys were conducted in a longitudinal household sample of adolescents recruited in 2013 (average age of 20 at wave 6 follow-ups). The analytic sample included 1177 female and male respondents representative of their age group in the USA at baseline. Latent classes were estimated based on 10 indicators of childhood adversity. Respondents were assigned to classes using posterior probabilities of latent class membership, and class membership was used to predict psychological outcomes in multivariable models. Three latent classes of childhood adversity were identified in the current sample, representing low childhood adversity (81.5%), higher probability of family dysfunction with lower levels of interpersonal abuse (13.4%), and high adversity including higher probabilities of parental discord and violence as well as child abuse (5.1%). Both classes of respondents who faced greater childhood adversity were more likely to report greater loneliness and lower optimism in emerging adulthood. Results were attenuated by measures of emotional well-being. Addressing adolescent loneliness and supporting optimistic outlooks in emerging adulthood are two pathways with potential benefits to reduce mental and physical morbidities.