The Pregnancy Risk Assessment Monitoring System (PRAMS) was established by the Centers for Disease Control and Prevention (CDC) in 1987 in five states, and today 32 states participate. Using states' vital statistics (birth certificates) as its population-based sampling frame, PRAMS "follows back" a stratified sample of women several months post-partum, surveying them about their own and their infant's prenatal, birth, and post-partum behavior and experiences. It uses a standardized protocol and multiple data collection modalities. PRAMS was initiated in an era of intense state and national interest in infant mortality, racial disparities reduction, and publicly supported prenatal care program expansion-and a lack of state-specific information available to inform local and state program development and assessment. The PRAMS format allows more in-depth inquiry about reproductive health topics than is possible from the more widespread but limited set of information available on birth certificates. PRAMS carries on a long, proud tradition of follow-back studies in the maternal and child health (MCH) field. In the 1920s, the U.S. Children's Bureau conducted the nation's first major in-depth study on infant mortality using a similar follow-back methodology. In each of 10 cities, every woman whose infant had died in the past year was systematically surveyed. The results provided an initial understanding of the nature of infant mortality in the U.S., indicating that infant deaths occurred more often in lower-income than higher-income families, among bottle-fed than breast-fed infants, and among twins than singletons. Beginning in 1964 and every eight years thereafter through 1988, the National Center for Health Statistics (NCHS) conducted intensive national follow-back studies of live births and infant/fetal deaths, which has provided much of our more recent national epidemiologic information about pregnancy and births, especially concerning smoking, prenatal care usage, etc. A similar Department of Education/NCHS national follow-back and longitudinal follow-up study, the Early Childhood Longitudinal Study-Birth Cohort (ECLS-BC) was begun in 2001 and will survey 10,000 mothers and their infants through kindergarten age.