This study used linked maternal-child data from the 1997-1998 National Longitudinal Survey of Youth to explore the wellbeing of children born to teenage mothers. Two econometric techniques explored the causal impact of early childbearing on subsequent child and adolescent outcomes. First, a fixed-effect, cousin-comparison analysis controlled for unobserved family characteristics that might influence child outcome. Second, outcomes among children born to women who had miscarriages during adolescence were examined. Results found that teen childbearing played only a small, if any, causal role in children's performance on standardized tests, use of marijuana, and fighting. Pre-birth characteristics of teen mothers, birth order, and family size were more important factors in determining these outcomes. For grade repetition, early sexual initiation, and truancy, the fixed effects and miscarriage analyses produced differing results. Teen childbearing had no statistically significant results for any outcomes in the miscarriage analysis. However, results suggested that teen childbearing related to grade repetition, truancy, and possibly early initiation of sexual activity. Results indicate that teenage mothers share more in common with young women who have miscarriages than with their own siblings who delay childbearing. It is those commonalities that drive the zero-order association between early fertility and several negative behavioral consequences for offspring. (Contains 27 references.) (SM)