Background: Adverse birth outcomes are more common among adolescent versus adult mothers, but little is known about school-based services that may improve birth outcomes in this group. Methods: Data from Waves I and IV of the National Longitudinal Study of Adolescent Health were analyzed. Girls and women who gave birth to singleton live infants after Wave I and before age 20, were still in secondary school while pregnant, and had complete data (N = 402) were included. Mothers reported infants' birthweight and gestational age. School administrators reported whether family planning counseling, diagnostic screening (including sexually transmitted diseases [STDs]), STD treatment, and prenatal/postpartum health care were provided on-site at school at Wave I. Multilevel models adjusted for individual and school characteristics were conducted. Results: Few schools offered reproductive health care services on-site. In multilevel analyses, availability of family planning counseling (Est. ß = 0.21, 95% confidence interval [CI] 0.04-0.38 p < 0.05) and prenatal/postpartum health care (Est. ß = 0.21, 95% CI 0.02-0.40 p < 0.05) were significantly associated with increased infant birthweight. No services examined were significantly associated with increased gestational age. Conclusions: Some school-based reproductive health services may improve subsequent birth outcomes among adolescent mothers. Future analyses should examine the mechanisms by which services impact birth outcomes.