Approximately 400,000 teenagers have children each year with reason to believe, through documented literature, that this early childbearing has profound consequences for the families involved. One of the most serious of these consequences is that children of young mothers have elevated risks of engaging in delinquent and antisocial behavior. This study, supported by the U.S. Department of Justice, Office of Juvenile Justice and Delinquency Prevention, the National Institute of Drug Abuse, and the National Science Foundation, summarizes previous research about the delinquent and antisocial tendencies of children born to young mothers. It then provides a comprehensive investigation of the early first-birth effect that was conducted in prior studies. The analysis is based on a contemporary community sample drawn from the city of Rochester, NY. The Rochester Youth Development Study was a multiwave panel study of adolescent development. The analysis investigated five interrelated hypotheses: (1) children born to mothers who began childbearing early are at higher risk for delinquency than children whose mothers delayed the onset of childbearing; (2) children born to mothers who began childbearing at very early ages, 18 and under, would have a higher risk of criminal behavior than those children born to mothers who began childbearing between the ages of 19 and 20 or who delayed onset childbearing until adulthood, age 21 or older; (3) the elevated risk of crime associated with being born to a young mother would be larger for male children than it is for female children; (4) larger for White children than for African-American or Hispanic children; and (5) the early first-birth effect would be mediated by resultant disruptions in family structure, parenting style, and financial well-being. Extending the central finding that children born to mothers who begin childbearing as teenagers are at risk for delinquency, the five tested hypotheses found: (1) a strong early first-birth effect, but not an effect for the mother’s age at the birth of the focal subject; (2) children born to mothers who began childbearing in their pre-adult years (under age 21) were prone to general delinquency, a mild early first-birth effect, and those born to mothers who began childbearing during their school-aged years (under age 19) were further prone to more serious forms of delinquency and a strong early first-birth effect; (3) that the early first-birth effect is be larger for male children than for female children; (4) the early first-birth effect was substantially larger for White and Hispanic male children than for African-American male children; and (5) the largest mediating effect was found in the number of family transitions. Appendices and references