Lesbian, gay, bisexual, transgender, or questioning (LGBTQ) students often face considerable isolation, discrimination, and violence at school, which can exacerbate the acute psychosocial and academic problems they already encounter. The purpose of this article is to introduce gay-straight alliances (GSAs) as a social justice and advocacy approach for professional school counselors to support LGBTQ students. GSAs are student-led non-curricular groups that provide support and advocacy for LGBTQ middle and high school students as well as their allies. The history of GSAs and research about these groups will be presented along with resources and recommendations for school counselors to become social justice advocates for their LGBTQ students. (Contains 20 online resources.)