The study found that the children of later adolescent mothers (18-19 years old at childbearing), not early/mid-adolescent mothers (13-17 years old at childbearing), showed the poorest outcomes for academic and behavioral trajectories. The children of the early/mid-adolescent mothers fared more poorly than the reference group (emerging adult mothers) only for the math achievement outcome. These findings are consistent with earlier studies. The authors speculate that these findings are due to the likelihood that younger teen mothers are more likely than older teen mothers to live with their children in their parents' home, where they may receive more assistance in childrearing. There was no evidence that family functioning mediated the detrimental effects of adolescent childbearing on math or the three behavioral outcomes (anxiety-emotional disorder, property offenses, and attention-deficit/hyperactivity disorder). The fact that the detrimental effects of adolescent childbearing held for math scores and property offenses even after accounting for family socioeconomic characteristics and family functioning suggests the importance of encouraging the delay of childbearing beyond the adolescent years. The study focused on longitudinal data collected on youth between 10 and 15 years old during the first four cycles of the Canadian National Longitudinal Survey of Children and Youth (1994-95, 1996-97, 1998-99, and 2000-2001). Maternal age at childbearing was classified according to four developmental periods: early to mid-adolescence (13-17 years old), late adolescence (18 to 19 years old), emerging adulthood (20-24 years old), and adulthood (25 to 29 years old). The survey measured youths' academic competency in math, anxiety-emotional disorder, property offense, hyperactivity-inattention, family socioeconomic status, parenting behaviors, and maternal depression. 6 tables, 1 figure, and 75 references