Efforts to prevent perinatal mortality and morbidity are traditionally directed at the pregnant woman. It is during the prenatal period that the mother's health status is closely monitored; her exposure to substances known to be harmful to the fetus is assessed, and intensive patient education on behaviors likely to benefit the unborn child is offered. Unfortunately, the initiation of prenatal care may already be too late to prevent spontaneous abortions, congenital anomalies, and some causes of low birthweight. Until routine prepregnancy care is available to all women of childbearing age, many opportunities for the primary prevention of poor reproductive outcomes will be lost. This paper describes the rationale for prepregnancy or preconceptional counseling and the specific purposes it should serve. A model program providing such services is described, and findings for a low socioeconomic population involved in the model program are given.