We examined the effects of short interpregnancy intervals on small-for-gestational age and preterm births in a biracial population using North Carolina birth certificate data from 1988 to 1994. We defined small-for-gestational age birth as being below the 10th percentile on a race-, sex-, and parity-specific growth curve after a gestation of 37–42 weeks. We defined preterm birth as a gestation of less than 37 weeks. We analyzed birth records from all eligible singleton births to black or white women ages 15–45 years after an interpregnancy interval of 0–3 months (N = 11,451) and a random sample of singleton births after an interval of 4–24 months (N = 23,118). We defined interpregnancy interval exposure categories as 0–3, 4–12, and 13–24 months. The multivariate adjusted odds ratio for small-for-gestational age births after interpregnancy intervals of 0–3 months compared with 13–24-month intervals was 1.6 (95% confidence interval = 1.4–1.8). The odds ratio for preterm birth after interpregnancy intervals of 0–3 months was 1.2 (95% confidence interval = 1.1–1.3). Odds ratios did not vary substantially by race for either outcome. (Epidemiology 1999;10:250–254)