Research on health care disparities is making important descriptive and analytical strides, and the issue of disparities has gained the attention of policymakers in the United States, other nation-states, and international organizations. Still, disparities research scholarship remains US-centric and too rarely takes a cross-national comparative approach to answering its questions. The US-centricity of disparities research has fostered a fixation on race and ethnicity that, although essential to understanding health disparities in the United States, has truncated the range of questions that researchers investigate. In this chapter, we make a case for comparative research that highlights its ability to identify the institutional factors that may affect disparities. We discuss the central methodological challenges to comparative research. After describing current solutions to such problems, we use data from the World Values Survey to show the impact of key social fault lines on self-assessed health in Europe and the United States. The negative impact of socioeconomic status (SES) on health is more generalizable across context, than the impact of race/ethnicity or gender.