Patterns of poorer health are observed in numerous groups within the US population. The Healthy People 2020 initiative provides a national framework to improve the health of all people in the USA. One of the four overarching goals of Healthy People 2020 is to achieve healthy equity, eliminate disparities, and improve the health of all groups including, lesbian, gay, bisexual, and transgender (LGBT) people. To achieve this goal for LGBT populations requires that these groups be identified in national health surveys. Sexuality, however, is a complex phenomenon that incorporates numerous, even contradictory, meanings, attitudes, and types of experiences, creating a major challenge in developing a single measure that is both meaningful and comparable across various socio-cultural groups throughout the US population. Without quality data, the picture of LGBT health, as it is portrayed through official statistics, is distorted. We contend that the specific construct of sexual identity (i.e., how individuals identify and conceptualize their own selves) is a key construct necessary for tracking health disparities. In this paper, we assess the validity of sexual identity measures using qualitative data from cognitive interview studies as well as estimates produced from the National Survey of Family Growth and the National Health and Nutrition Examination Survey.