The gap between black and white infant death rates in the United States has grown over the last three decades. Epidemiologic and medical studies by investigators seeking to understand and reverse this adverse trend have been unsuccessful. Researchers have looked in vain for the combination of social and environmental risk factors that are more common among blacks and would therefore explain this group's poor reproductive outcomes. The implicit alternate hypothesis is genetic differences between blacks and whites. In fact, there is more of a gap between black and white mothers of higher socioeconomic position than between overall black and white rates without socioeconomic stratification. An alternative to the genetic theory explains these results, however, on the basis of social risk factors that, because of the presence of widespread discrimination in the society under study, apply only to blacks. Such factors are the effects of racism, not race per se. Several lines of research are needed to investigate the effects of racism on perinatal outcomes, including studies on psychophysiological reactions to racial discrimination and on ethnic group differences in coping mechanisms, social supports, and physical environment. Analysis of trends over the past 37 years indicates that improvements in white (and total US) infant mortality rates cannot be anticipated until the racial gap is closed.