The purpose of this study is to review samples from research on gay, lesbian, and bisexual (GLB) issues and to evaluate the suitability of this body of research to support affirmative and evidence‐based practice with GLB clients. The authors systematically reviewed the sampling methodology and sample composition of GLB‐related research. All original, quantitative articles focusing on GLB issues published in couple and family therapy (CFT)‐related journals since 1975 were coded (n = 153). Results suggest that within the GLB literature base there is some evidence of heterocentrism as well as neglect of issues of class, race, and gender. Suggestions to improve the diversity and representativeness of samples—and, thus, clinical implications—of GLB‐related research in CFT literature are provided.