This article suggests that while disparities in infant mortality have been longstanding, the mechanisms of disparity creation are undergoing intense change. This dynamic character is explored by first developing an analytic model that examines the interaction between social factors and the public health and clinical capacity to intervene. Disparities in infant mortality are then broken down into their component parts and linked to specific arenas of intervention. Disparities in postneonatal mortality are being shaped by differential access to interventions designed to prevent infant death from congenital anomalies and the Sudden Infant Death Syndrome. Disparities in neonatal mortality are primarily determined by factors that influence the birthrate of extremely premature infants and access to specialized obstetrical and pediatric care. This analysis suggests that the epidemiology and social meaning of disparities in infant mortality are intensely dynamic and increasingly reflect the interaction between social forces and technical innovation.