School-based sports and physical education play an important role in the development of youth (Jones, Edwards, et al., 2017), but participation in athletics is unequal for lesbian, gay, bisexual, transgender, and queer (LGBTQ) youth compared to their straight/cisgender peers [Greenspan, S. B., Griffith, C., & Murtagh, E. F. (2017). LGBTQ youths' school athletic experiences: A 40-year content analysis in nine flagship journals. "Journal of LGBT Issues in Counseling," 11(3), 190-200]. Sport cultures, generally, recreate dynamics of exclusion for marginalized youth. However, there are opportunities to transform these spaces into more inclusive and positive environments to support positive growth for all young people [Newman, T., Alvarez, A., & Kim, M. (2017). An experiential approach to sport-based positive youth development. "Journal of Experiential Education," 40(3), 308-322]. Our study uses a data set of adolescents, collected as part of a community-based participatory action research project led by high school students in southeast Michigan, USA. Respondents reported their sexual and gender identities, as well as experiences in youth sport, as well as safety using sex-segregated facilities (i.e., bathrooms and locker-rooms). Using mediation models based on linear regression, we found evidence that LGBQ high school students play sports at a significantly lower rate compared to straight students, and among those who play sports, LGBTQ respondents felt significantly less safe compared to straight and cisgender students. Opposite to the LGBQ and trans youth in this study, straight/cisgender youth also reported feeling safer using all facilities. The mediation models suggest that these inequalities help to explain disparities in rates of sports participation and feelings of safety while participating. These findings have important implications for policy, practice, and future research.