Sexual and gender minority (SGM) people are underrepresented in psychological research—including personality and relationship sciences. Part of this underrepresentation likely stems from potential participants’ unwillingness to join a study, but more concerningly, researchers explicitly exclude data from SGM participants. Arguments for SGM exclusion often rest upon the difficulty of recruitment, as well as differences in outcomes, such as depression, and experiences, such as discrimination ([anonymized, 2023]). However, mean-level differences in dependent or independent variables do not necessarily bias estimating population effect sizes. What is often implied, but less explored, is the extent to which correlational differences may exist between groups. Applying the framework of the Gender Similarities Hypothesis (Hyde, 2005), we compare means, variances, and correlations across a range of psychosocial variables between SGM and non-SGM participants (N = 1,743). Consistent with an expansive application of the Gender Similarities Hypothesis, we find that means, variance, and correlations are largely similar across categorical identities related to both gender and sexual orientation. These results support a general expectation that similarities between groups are more common than differences in normative psychological processes, although clear differences in means and variances exist for specific experiences and outcomes. The implication of this work informs the inclusion of diverse sexual and gender identities in basic psychological research. Further, the findings speak to the generalizability of past research to populations historically underrepresented in psychological science.