This study compared the well-being of children born to mothers younger than 17 years old(very young teens), 18 to 19 years old (older teens), and mothers in their early twenties. Measures of well-being were assessed in five domains: (1) health and psychological well-being; (2) quality of home environment; (3) cognitive development and educational attainment; (4) behavior problems and substance abuse; and (5) sexual experiences and first births. The study also examined the effects of mother's age at first birth on child well-being. Data were drawn from the Longitudinal Survey of Youth-Child Supplement (NLSY-CS) and the National Survey of Children (NSC). Major findings indicated that although controlling for maternal background characteristics reduced the effects of teen motherhood on child well-being, the deleterious effect of being born to young teens remained statistically significant on children's cognitive achievement scores, grade repetition, teacher rating of school performance, and home environment quality. The deleterious consequences of teen childbearing extended to their subsequent children. There was a persistently negative effect of early childbearing in the cognitive domain. The NLSY-CS revealed that 4- to 14-year-old children of the youngest teens performed more poorly on tests of cognitive ability, and NSC results showed that the offspring of teens were more likely to be retained and less likely to be perceived by their teachers as performing favorably in high school. Behavior difficulties such as running away, early sexual activity, and teen motherhood emerged among children in the NSC. (Contains 20 references.) (Author/JC)