​The California Health Interview Survey (CHIS) represents one of the largest ongoing population-based data collection efforts in the country that has included measurement of sexual orientation for more than a decade. In this June 17 seminar, Gary Gates, the Blachford-Cooper Distinguished Scholar and research director at the UCLA Williams Institute, demonstrates how CHIS has been used in research about the lesbian, gay, bisexual and (as of CHIS 2015) transgender community and the role it has played in helping to inform important policy debates about LGBT rights. He also highlights new ways that CHIS is expanding its efforts to identity the LGBT population and provide leadership in advancing efforts to improve LGBT data collection.