Increasing evidence indicates that the roots of health inequalities lie in an array of social, economic, and political attributes of nation-states. In this study, the authors identify contributions to income-related inequalities in self-reported health in the United States and Canada. Data are from the 2002 to 2003 Joint Canada-US Survey of Health. The authors conclude that individual-level health risk factors and health care system characteristics have similar associations with health status in both countries, but they both are far more prevalent and much more concentrated among lower-income groups in the United States than in Canada.