PROJECT SUMMARY Reliable and efficient methods of measuring sexual and gender minority (SGM) status, that are acceptable to both SGM and non-SGM people, are needed so that researchers can more accurately capture and better understand the health of SGM individuals. Current measures are limited in how they operationalize assessment of the many constitutive domains of sexual orientation and gender identity (SOGI), the diversity of answer choices, and in accounting for changes in SOGI domains over one’s life. Further, the sexual orientation domains (i.e., attraction, identity, behavior) and gender domains (i.e., gender identity, gender expression) evaluated often result in wide variation in SGM population estimates, discrepancies in health risk factors, experiences, and outcomes. To more accurately identify SGM people, measures must ultimately be intelligible and acceptable to the entire population. The importance of this was underscored after the 2010 Census, where mismarks on the sex question by opposite-sex couples led to inflated estimates of same-sex households. Until well tested, reliable, and community-acceptable measures are developed, SGM individuals will continue to be underrepresented and understudied in research. Non-SGM individuals will also continue to be miss-measured and overburdened. In this proposal, a mixed methods approach for developing and describing the performance characteristics of a reliable, low-burden, community acceptable SGM status screening question is outlined. Leveraging two large national cohorts, response accuracy within this strategy as well as participant understanding and acceptability will be measured through iterative quantitative testing among both SGM and non-SGM individuals. The overall hypothesis is that using a screener question of SGM status followed by more specific follow-up testing with expanded answer choices for SGM individuals will decrease survey burden for non-SGM people while also allowing SGM people to be identified and affirmed. First, a broadly acceptable SGM screening question will be developed and piloted using cognitive interviews and online pilot testing. The best performing screening question will then be compared head-to-head with simultaneous administration of two set of SOGI measures. Finally, the SGM status screening question and existing confirmatory SOGI measures’ stability and acceptability over time will be analyzed to evaluate performance characteristics and demographic differences in answer choice patterns. Accurate identification and inclusive data collection are critical to improving outcomes and reducing disparities. In summary, the proposed research will develop a high-performing, efficient strategy for identifying SGM people.