This study examined high school counselors' education and training, counseling competency, and supportive behavior regarding gay, lesbian, and bisexual students. Sexual minority students often face a range of school and mental health problems. Results show that participants' counseling competency skills, knowledge, and attitudes predict affirmative behavior. Counseling competency also mediates the relationship between sexual orientation education/training and affirmative behavior. This article concludes with recommendations for preparing school counselors to work with gay, lesbian, and bisexual youth.