Use and abuse of both licit and illicit drugs is common. Although certain variables can appropriately serve as markers for increased risk, the possibility of substance abuse should be considered in all pregnant women. Alcohol is the leading identified cause of teratogenesis by drugs or environmental agents; most other drugs of abuse do not increase the risk of congenital malformations on a large scale. Substance abuse can produce significant degrees of toxicity in both pregnant women and their offspring. Screening and counseling of pregnant women concerning past and present use of tobacco, alcohol, and illicit drugs should be routine. Prenatal care must include increased surveillance for drug-related complications; coordinated, comprehensive, family-oriented drug treatment; and social services. Rehabilitation and support efforts should continue after delivery and address issues that lead to and maintain patterns of abuse. The drug-exposed neonate must be anticipated and evaluated with a knowledge of the maternal drug abuse history and specific drug risks, including neonatal abstinence syndrome. Continuing care of the child should address the increased risk of developmental and behavioral problems from both prenatal exposures and continuing socioenvironmental barriers.