The Mothers Project is a clinical epidemiological study of the correlates of cocaine and other drug abuse during pregnancy and a controlled clinical trial in which cocaine-dependent women are randomized into one of two treatment programs, an enhanced primary care treatment program or a comprehensive day treatment program that provides family support services and child care. Routine drug abuse screening in a hospital-based prenatal clinic uses structured interviews and urine testing to identify cocaine users and enroll them in the clinical trial. Assessments of mother and child are made at 3, 6, 9, 12, 18, and 24 months. A database system has been developed to meet the needs of the clinical trial component of the Mothers Project. The database design is based on functional and performance specifications. The administrative component of the data base is intended to monitor and contact subjects. Administrative data are stored in three data sets called mother, pregnancy, and child tables. In contrast to administrative functions requiring record-based processing, questionnaire and clinical data intended for analysis are processed at the data set level in batches. Database management functions are arranged into administrative and analysis task groups. The administrative database system uses relational database technology, while the analysis database system employs more traditional flat-file methods. 3 references and 4 figures