Sexual and gender minority (SGM) individuals endure a number of health disparities, such as higher rates of violence, mental health conditions, and medical concerns. These disparities are exacerbated by the fact that SGM individuals face stigmatizing health care provider and system-related experiences. The primary purpose of this study was to quantify health service providers' SGM health competency by developing a measure, namely the Health Care Competency Assessment Form-Sexual and Gender Minority Patients (HCAF-SGM). Further, we examined correlates of SGM health competency based on leading theories of prejudice, primarily the dual process model of prejudice and social identity theory. The study comprised two phases: item development and pilot testing, followed by a primary online survey administration with several health care professionals and training organizations (N = 155). Study findings supported a one-factor HCAF-SGM score, suggesting that health care providers view their competency regarding SGM individuals in a holistic manner, without differentiating between knowledge, attitude, and skill. The measure was found to be negatively associated with right-wing authoritarianism and positively correlated with specific social identities most salient to the topic of SGM health (i.e., health care professional and SGM). The HCAF-SGM shows promise as a reliable and valid assessment of perceived provider health care competency. Implications for SGM health-related measurement, clinical supervision, and training are discussed. (PsycInfo Database Record (c) 2024 APA, all rights reserved).