We examined racial and income-related patterns of mortality from birth through adolescence in Boston, where residents have high access to tertiary medical care. Childhood mortality was significantly higher among black children (odds ratio, 1.24; P less than 0.05) and low-income children (odds ratio, 1.47; P less than 0.001). Socioeconomic effects varied for different age groups and causes of death. The largest relative disparity occurred in the neonatal and postneonatal periods, and the smallest in adolescence. Of the total racial differential in neonatal mortality (6.88 deaths per 1000 live births), 51.2 per cent occurred in premature infants, 13.4 per cent in term infants who were small for their gestational age, and 25.9 per cent in neonates who were both premature and small for their age. Black neonatal mortality was elevated at all income levels. Beyond the neonatal period, mortality from respiratory disease, fire, and homicide had strong inverse relationships with income, and mortality from injuries to the occupants of motor vehicles was directly related to income. These data suggest that despite access to tertiary medical services, substantial social differentiation in mortality may exist throughout childhood. Equity in childhood survival will probably require policies that emphasize preventive goals.