The Multigroup Ethnic Identity Measure (MEIM) is perhaps the most widely used and studied measure of ethnic identity, that is, the part of an individual’s self-concept derived from knowledge of membership in a social group along with the value and emotional significance attached to that membership. This conceptualization of group identity can also be applied to lesbian, gay, and bisexual (LGB) group identity, raising the possibility that the MEIM could be adapted to assess components of sexual minority identity. Ad hoc adaptations of the MEIM for this purpose have been used in research, but its factor structure has never been tested. The present study used data from 622 LGB university students to examine psychometric properties of an adapted version of the MEIM, which we called the Lesbian, Gay, and Bisexual Group Identity Measure (LGBGIM). We first used confirmatory factor analysis to test 4 models identified in previous research on the factor structure of the MEIM. Results indicated that none of these models was optimal when applied to the LGBGIM. Subsequent exploratory factor analyses yielded a 3-factor model that offered satisfactory fit and an interpretable pattern of factor loadings. Examination of reliability and validity estimates provided preliminary support for use of the LGBGIM as a measure of LGB group identity. Implications for using the LGBGIM in future research are discussed.