The present review examines the current status of efforts to reduce environmental tobacco smoke exposure (ETS) among infants and young children. Estimates of the number of children exposed vary, but it is probably over 20 million or about 35% of all U.S. children. Healthy People 2010 sets as an objective the reduction, to 10%, of the proportion of children regularly exposed to tobacco smoke at home. Children with ETS exposure are at higher risk for upper respiratory illnesses, asthma, otitis media, and sudden infant death syndrome. Eight experimental or quasi-experimental studies of attempts to reduce children' ETS exposure with sample sizes of greater than 100 were conducted in the United States and published between 1990 and 2003. Most of these studies showed a significant impact on maternal smoking and on the number of cigarettes smoked in the home, although intervention-control differences were relatively small. Despite support from professional organizations and federal government groups, many pediatricians and family physicians do not routinely engage in intensive efforts to reduce children's ETS exposure. Training in techniques for reducing tobacco dependence should be included in professional education programs. Public and private insurance should reimburse providers for efforts in this area. An overall strategy for reducing children's ETS exposure should combine individual counseling and education in offices, clinics, and homes with community education and regulatory and economic policies (i.e., smoking bans and excise taxes). Additional funding is needed for studies of provider knowledge, attitudes, and practices; of the effectiveness of various communication strategies; and of office- and community-based strategies to reduce ETS exposure.