Using data from the National Longitudinal Survey of Youth, this article examined how early maternal characteristics, an adolescent's family environment, and the adolescent's own attitudes and behaviors were associated with the odds of a nonmarital teenage birth among youth born to teenage mothers. Multivariate analyses indicated that these domains were closely linked. Early maternal characteristics shaped the later family environment of adolescents (parenting quality and home environment), which, in turn, was associated with the attitudes and behaviors of teens that put them at risk of a nonmarital birth. Notably, there was variation in some of the associations by gender. Increased mother's cognitive ability lowered the risk of a nonmarital birth for boys, but not for girls, whereas fertility expectations were significant for girls, but not for boys. There were no race-ethnic differences in the risk of a teenage birth among girls, although Black boys had a higher risk than White boys. (Contains 4 tables.)