Despite the well-established link between juvenile delinquency and socioeconomic attainment in adulthood, less is known about whether engagement in delinquent behavior during adolescence shapes adult health outcomes. This study examines the association between juvenile delinquency and adult physical and mental health, and whether this association is confounded by unobserved family heterogeneity. Moreover, this study explores the potential underlying mechanisms through which juvenile delinquency shapes adult physical and mental health. Using data from the National Longitudinal Study of Adolescent to Adult Health (Add Health) 1994-1995 (Wave 1) and 2007-2008 (Wave 4), we adopted a sibling fixed effect approach to account for genetic factors, family environment, and childhood social contexts such as school and neighborhood effects. The conventional OLS results show that engagement in delinquent behavior during adolescence strongly predicts higher levels of Framingham cardiovascular disease (CVD) risk score and depressive symptoms in adulthood. Once we account for family-specific heterogeneity, however, the point estimates of the associations of delinquency with CVD risk score and depressive symptoms are attenuated by 33% and 45%, respectively. Despite this attenuation, the association of juvenile delinquency with adult health is robust: a one standard-deviation increase in juvenile delinquency is associated with approximately 8 and 6 percent of one standard-deviation increases in CVD risk and depressive symptoms, respectively. Our mediation analyses suggest that a combination of several mediating pathways jointly explain the association between juvenile delinquency with adult health. The most consistent and significant mediating pathways connecting juvenile delinquency to both physical and mental health included disruption in student-teacher relationship, smoking, criminal justice contact, and educational attainment. Moreover, while binge drinking explained part of the association between delinquency and CVD risk score, student-friend relationship partially mediated the association with depression.Copyright © 2020 Elsevier Ltd. All rights reserved.