From a health equity standpoint, one of the most important provisions of the Affordable Care Act is the requirement that all health and health care institutions that receive federal funds must collect data on the race, ethnicity, and primary language of the patients they serve. Having this information will allow policymakers, researchers, and advocates understand when, where, and under what circumstances health and health care inequities may occur. There is disagreement in the field, however, about how to collect this data, and even about what the terms "race" and "ethnicity" mean. In response to the U.S. Department of Health and Human Services' call for comments, the Joint Center prepared a letter to Secretary Kathleen Sebelius outlining some considerations for the collection of race and ethnicity data