Topic: This critical review of the literature integrates findings across varied literatures and identifies areas for continued study on the prevalence, correlates, and impact of substance use (alcohol and illicit drugs) on social role functioning among emerging adults with serious mental health conditions. Purpose: This population is of interest because of high comorbidity rates between substance use and serious mental health conditions and the added difficulties posed by their co-occurrence during the transition to adulthood. This critical review presents the epidemiology of substance use in emerging adults with serious mental health conditions compared to emerging adults without these conditions, as well as what is known about predictors and consequences of substance use in this population. Sources Used: PsychINFO and PubMed along with relevant published literature. Results: This review summarizes what is known about the impact of these cooccurring problems on the transition of emerging adults from school and training environments to adult work roles. Though this group presents with unique challenges, few programs have been developed to address their specific needs. This paper synthesizes what is known empirically about approaches with this population, discussing those that might be useful for emerging adults with comorbid serious mental health conditions and substance use problems, particularly in supporting their educational and vocational development. Conclusions and Implications for Practice: Emerging adults with co-occurring serious mental health conditions and substance use problems are underserved by current mental health systems. Recommendations focus on how to promote mental health and social role functioning through comprehensive intervention programs that provide continuity of care through the transition to adulthood.