<p>Social workers are on the frontlines of delivering psychological and social services to lesbian, gay, and bisexual (LGB) clients to help mitigate distress caused by stigma. Developing competence in LGB-affirmative practice, which includes acceptance of LGB identities and attention to the harmful effects of stigma-related stressors, is essential for effective service provision. However, research in this area has often relied on self-report surveys, which are prone to social desirability bias. Moreover, organizational factors such as religious affiliation, inclusion and diversity policies, and the presence of an LGB-friendly climate have received relatively little attention. This study aimed to assess LGB affirmative practice competence and examine its correlates in a non-probability sample of social workers practicing in Hong Kong and Taipei/New Taipei City. Between March and August 2024, a total of 321 social workers (mean age = 33.38, SD = 7.27; 67% female; 36% non-heterosexual) participated in an online survey and vignette-based assessment. The vignette responses were evaluated by multiple coders to assess participants’ case conceptualization and reflexivity in working with LGB clients. Findings revealed an overall low to moderate level of LGB affirmative practice competence among participants. Significant correlates included the number of LGB-related training hours received and the number of LGB clients served. The study demonstrates the utility of vignette-based assessments in measuring practice competence and suggests training and simulation as effective strategies for enhancing social workers’ LGB affirmative practice competence.</p>