There is little consensus about the meaning of the terms “health disparities,” “health inequalities,” or “health equity.” The definitions can have importantpractical consequences, determining the measurements that are monitored by governmentsand international agencies and the activities that will be supported by resourcesearmarked to address health disparities/inequalities or health equity. This paper aims toclarify the concepts of health disparities/inequalities (used interchangeably here) andhealth equity, focusing on the implications of different definitions for measurement andhence for accountability. Health disparities/inequalities do not refer to all differencesin health. A health disparity/inequality is a particular type of difference in health (or inthe most important influences on health that could potentially be shaped by policies);it is a difference in which disadvantaged social groups—such as the poor, racial/ethnicminorities, women, or other groups who have persistently experienced social disadvantageor discrimination—systematically experience worse health or greater healthrisks than more advantaged social groups. (“Social advantage” refers to one’s relativeposition in a social hierarchy determined by wealth, power, and/or prestige.) Healthdisparities/inequalities include differences between the most advantaged group in agiven category—e.g., the wealthiest, the most powerful racial/ethnic group—and allothers, not only between the best- and worst-off groups. Pursuing health equity meanspursuing the elimination of such health disparities/inequalities.