Early age‐of‐onset delinquency and substance use confer a major risk for continued criminality, alcohol and drug abuse, and other serious difficulties throughout the life course. Our objective is to examine the developmental roots of preteen delinquency and substance use. By using nationally representative longitudinal data from the UK Millennium Cohort Study (N= 13,221), we examine the influence of early childhood developmental and family risks on latent pathways of antisocial tendencies from 3 to 7 years of age, and the influence of those pathways on property crime and substance use by 11 years of age. We identified a normative, nonantisocial pathway; a pathway marked by oppositional behavior and fighting; a pathway marked by impulsivity and inattention; and a rare pathway characterized by a wide range of antisocial tendencies. Children with developmental and family risks that emerged by 3 years of age—specifically difficult infant temperament, low cognitive ability, weak parental closeness, and disadvantaged family background—face increased odds of antisocial tendencies. Minimal overlap is found between the risk factors for early antisocial tendencies and those for preteen delinquency. Children on an antisocial pathway are more likely to engage in preteen delinquency and substance use by 11 years of age even after accounting for early life risk factors.