Previous studies of maltreatment of children born to women who used cocaine during pregnancy have relied on either selected samples of infants identified at birth or biased, high-risk samples referred to protective services. To determine the relative risk of either maltreatment or placement outside the home during the first 2 years of life in children born to women who used cocaine during pregnancy compared with a sociodemographically similar comparison group. We reviewed the medical records of consecutive deliveries at Yale-New Haven Hospital from August 1, 1989 through September 30, 1990. Of the 1140 women who were eligible for the study, 173 had a positive history and/or a positive urine test for cocaine; 139 of the infants were included in the study. A comparison group of infants was chosen from 526 women whose obstetric records indicated that they had not used cocaine during pregnancy based on at least two separate notations in the record. For each of the 139 cocaine-exposed infants, an infant was chosen from the comparison group based on seven matching characteristics: date of birth, race, method of payment for the hospitalization, gestational age, mother's parity, mother's age at delivery, and timing of the first prenatal visit. Children's medical records at the only two hospitals in the region, the two neighborhood health centers, and the only health maintenance organization were reviewed from birth to 2 years of age. Each injury was classified by two independent reviewers who used predefined criteria to distinguish maltreatment (physical abuse, neglect, or abandonment) from unintentional injuries. Placements outside the home were categorized according to whether the placement was in foster care or with a relative. The children were mainly African-Americans (80%), and most were enrolled in Medicaid (96.5%). By 2 years of age, 9.3% of the infants in the cocaine-exposed group versus 1.4% in the comparison group had been maltreated [matched relative risk = 6.5; 95% confidence interval (CI) = 1.47, 28.80], and 25.9% vs 8.6% had spent some time in placement (matched relative risk = 5.0; 95% CI = 2.08, 12.01). After controlling for differences between the groups in baseline clinical and social variables, the adjusted odds ratios for both maltreatment (3.98; 95% CI = .81, 22.80) and placement (1.66; 95% CI = .74, 17. 83) decreased and were no longer statistically significant. In this population-based study, children born to women who used cocaine during pregnancy were at a substantially increased risk of maltreatment or placement outside the home compared with a sociodemographically similar comparison group. Differences in baseline variables between the two groups, however, partially accounted for this increased risk. Therefore, a mother's use of cocaine is more likely a marker of increased risk rather than a single explanatory variable.