Background: Adverse childhood experiences (ACEs) are associated with behavioral health challenges and high school dropout, and behavioral health is associated with high school dropout. Less is known about the role of behavioral health challenges in the relationship between ACEs and high school dropout. Methods: Using data from the Panel Study of Income Dynamics (2013) and its 2014 Childhood Retrospective Circumstances Study supplement, the current study conducts mediational path analysis to examine the direct and indirect effects of cumulative ACEs on high school dropout via adolescent depression, anxiety, and substance use. Results: Experiencing more ACEs was associated with depression, anxiety, and substance use. Only depression and substance use were associated with high school dropout. There was a significant direct effect between increased ACEs and high school dropout and significant indirect effects via depression and substance use, but not anxiety. Conclusions: Adolescent behavioral health interventions to address the long-term effects of ACEs may also support academic achievement. School-based interventions, particularly those aligned with trauma-sensitive school frameworks and engaging various school personnel, including school nurses, should be considered. Community- and policy-level interventions aimed at primary prevention of ACEs are also needed.