Adverse childhood experiences (ACEs) can negatively impact adolescents’ academic, affective, behavioral, biological, cognitive, and social development. Disruptions to these domains are shown to increase the risk for significant behavioral and emotional difficulties, including depressive symptoms and problematic substance use. Despite efforts to expand the conceptualization of ACEs, minimal research has evaluated the cumulative impact of the 10 conventional ACEs (Felitti et al., 1998) and nine expanded ACEs (i.e., additional adversities and life stressors such as bullying, racism, neighborhood violence, living in foster care, separation from caregivers due to deportation; Burke Harris & Renschler, 2015) – referred to as extended ACEs here – on youth depression and substance use. Of the few efforts assessing extended ACEs, most rely on caregiver reports of adolescents’ ACE exposure. The present effort uses data from an adolescent-focused primary and behavioral health care practice and a sample of 1,183 youths between the ages of 12 and 17 years. The study aimed to (a) measure adolescents’ self-reported and caregiver-reported extended ACEs; (b) examine the association between extended ACEs and youth depressive symptoms and problematic substance use; and (c) evaluate whether caregiver-youth discrepancy in adolescents’ extended ACE exposure related to a difference in adolescent-reported depression and substance use. Results indicated that adolescents reported more extended ACEs than their caregivers reported for them. Both adolescent- and caregiver-reported extended ACEs were associated with depressive symptoms and substance use. Adolescent self-reports were a stronger predictor of depressive symptoms, though not of substance use, than caregiver reports. Although the direction of the caregiver-youth discrepancy significantly related to higher levels of depression and substance use (i.e., when adolescents reported more extended ACEs than their caregivers reported), the degree of the caregiver-youth discrepancy did not (i.e., the difference between reported extended ACEs). Youths endorsed a higher level of depression when dyads were in agreement at midrange levels of extended ACE exposure.Findings underscore the value of assessing extended ACEs and using multiple informants to understand the impact of ACEs on youth depressive symptoms and problematic substance use. Understanding these relationships may inform early detection, prevention, and treatment efforts, in addition to safeguarding adolescents’ developmental trajectories by reducing their risk for short- and long-term health consequences. Policymakers should consider ways to decrease youths’ extended ACE exposure across different levels of their ecologies, along with implementing policies that better support families.