BACKGROUND: Affirming spaces have been associated with improved mental health outcomes for lesbian, gay, bisexual, transgender, queer, and questioning (LGBTQ) adolescents. METHODS: With data from adolescents currently enrolled in middle or high school across the United States, this study used topic modeling methods to examine students' reports of what they were looking for in LGBTQ-affirming schools and, separately, the association of LGBTQ-affirming schools with suicide risk reduction. RESULTS: Topic models demonstrated consistent themes in how students determined that their school was affirming, such as LGBTQ clubs, teachers requesting pronouns, pride flags, and accepting peers. Students of color uniquely looked for actionable responses in addressing LGBTQ issues. Transgender and nonbinary students required explicit mention of support for transgender issues. Quantitatively, LGBTQ students who reported that their school was LGBTQ-affirming had 20% lower odds of attempting suicide in the past year (adjusted odds ratio = 0.80). CONCLUSIONS: These findings suggest that schools must be safe for all youth and implementing policies that make LGBTQ students feel seen and supported in their identities is a protective factor for mental health. IMPLICATIONS: School policies must ensure that youth have access to supportive people, symbols of support, and LGBTQ clubs and that they are also salient to LGBTQ students of color and transgender and nonbinary students.