This study explored the relationship between participant personality, self-reported Lesbian and Gay (LG) affirmative therapy competency and demonstrated LG affirmative therapy competency utilizing an online-analogue methodology with a sample of 255 therapists-in-training. Participants were randomly assigned to review one of four vignettes that varied the sexual orientation and presenting concern of the characters. The experimental design was a 2 (Gay/Lesbian Vignette) x 2 (Relationship/Adjustment Vignette) factorial with three dependent variables (i.e., case conceptualization ability, LGB affirmative therapy competency, and LGB affirmative therapy self-efficacy), and three covariates (i.e., participant personality, sexual orientation, and extent of relationships with LGBT individuals). We also explored the relationship between self-reported competency (i.e., scores on self-report measures of competency) and demonstrated competency (i.e., scores on case conceptualizations of LG vignettes). Contrary to the hypotheses the groups did not differ significantly on their case conceptualization ability or self-reported competency based on receiving a lesbian versus gay vignette, nor did they significantly differ when responding to a relationship versus adjustment concern after controlling for participant personality, extent of relationships, and sexual orientation. Additionally, consistent with previous research in the general multicultural literature (e.g., Constantine & Ladany, 2000), we found no significant relationship between most self-report measures of competency and case conceptualization ability. The findings from this study provide several implications for future research, scale development, practice, and training in LG affirmative therapy.