Supportive school and community resources are associated with reduced risk of suicidality among lesbian, gay, bisexual, transgender, and queer/questioning (LGBTQ +) adolescents as well as their cisgender, heterosexual peers. This study examined whether adolescents attending schools and living in communities with more versus fewer LGBTQ +-supportive resources were at lower risk of a past-year suicide attempt. Data on sexual orientation and past-year suicide attempt were obtained from student surveys administered in 30 Massachusetts public high schools between 2014 and 2017 (N = 20,790). Data on school resources were obtained from a questionnaire administered to school officials, and community resources were assessed through internet searching. Modified Poisson generalized estimating equations tested associations between school and community LGBTQ +-supports and suicide attempt separately by sex/gender, adjusting for student, school, and community covariates. Several school resources and the availability of community-wide LGBTQ +-supportive resources were associated with lower risk of a suicide attempt among several subgroups of students, even after controlling for the presence of multiple school and community resources and covariates. For example, the risk of a suicide attempt among gay, bisexual and questioning boys in schools with a gender-neutral restroom was approximately half compared to gay, bisexual and questioning boys in schools without this resource. Past year suicide attempts were also significantly lower among questioning, RR = 0.56, CI [0.37-0.86], and heterosexual, RR = 0.59, CI [0.50-0.68], girls living in communities with more supportive resources compared to those in communities with fewer resources. LGBTQ +-supportive resources in schools and communities may be beneficial for all adolescents regardless of sexual orientation. (PsycInfo Database Record (c) 2021 APA, all rights reserved).