National vital statistics in the United States are unique among those of advanced capitalist countries in reporting data only by race, sex, and age--not by class and income. This article reviews the limited U.S. data resources that may be used to document social class inequalities in health. Summarizing the strengths and weaknesses of the British approach to gathering data on social class and health, the authors discuss possible approaches to collecting data that could be feasible in the U.S. context. They argue that educational level is an insufficient marker for socioeconomic position and contend that appropriate measures must take into account not only individual but also household and neighborhood markers of social class. These additional types of social class data are especially important for accurately describing and understanding social class inequalities in health among women and across diverse racial/ethnic groups.