This paper describes the methods of the Maternal Health and Child Development of Project at the Boston City Hospital which explored the impact of maternal drinking prior to and during pregnancy on fetal development. Between February 1977 and October 1979, of 3222 women who delivered single infants, 1690 were interviewed in hospital after delivery and their babies examined by a pediatrician who was unaware of the interview results. The 1690 mother-infant pairs of whom both interview and exam are available did not systematically differ from the 272 for whom the interview only or 824 for whom the exam only was conducted. Interviews were also collected prenatally in the Boston City Hospital's Women's Clinic, from 470 women whose infants were examined. Maternal and infant characteristics are described. Heavy drinkers were much more likely to smoke cigarettes and to have used psychoactive drugs than lighter drinkers. Heavy drinkers also differed from non-heavy drinkers on several other factors which may influence fetal development.