["\nAbstract\nEarly pubertal timing (PT) increases the risk of adolescent delinquency, whereas late development reduces this risk; however, the mechanisms explaining PT effects on delinquency remain elusive. Theoretically, the PT–delinquency relationship is as a result of changes in parental supervision, peer affiliations, and body‐image perceptions or is a spurious reflection of early life risk factors. Using intergenerational data from the Millennium Cohort Study, a prospective sample of children followed from infancy to age 14 years in the United Kingdom (N = 11,556 parent–child pairs), we find that for both boys and girls, early PT is associated with heightened risks of delinquency, relative to on‐time puberty, whereas late PT is associated with lower risks, even after controlling for a large share of childhood confounders. Mediation test results indicate that changes in parental supervision, peer affiliations, and body‐image perceptions from ages 11 to 14 partly account for associations between off‐time PT and delinquency. Our findings are most consistent with criminological theories in which the psychosocial, familial, and peer group changes that accompany off‐time pubertal development are emphasized. Changes in peer substance use, in particular, were the primary explanatory factor for the relationships between early and late PT and delinquency, for both boys and girls.\n", "Criminology, Volume 58, Issue 3, Page 537-567, August 2020. "]