Lesbian, gay, bisexual, transgender, and queer/questioning (LGBTQ) adolescents are more likely to report suicidality and worse mental health than their heterosexual peers. We conducted a systematic review to examine the relationship between positive school climate and suicidality and mental health among LGBTQ adolescents. We searched the literature using PubMed, PsycINFO, and CINAHL. Six studies met inclusion criteria, and all had low to moderate risks of bias. Results indicate that LGBTQ students in schools with more positive school climates were at lower risk of suicidality and reported fewer depressive symptoms compared to students in less positive school climates. Being at the forefront of health in schools, school nurses have the opportunity to advocate for changes in school environments that promote positive mental health for all youth, including LGBTQ adolescents.