In this study, we questioned how high school dress codes outlined in official handbooks were written or presented in regard to the gender binary, either/or perspective. We critically analyzed how or if they allowed for flexibility in expression of gender and sexual identity and if they supported, encouraged, or affirmed a variety of expressions, in particular transgender and gender non-conforming expressions, throughout the text or images. The content analysis method was used to analyze 735 handbooks from the 2016 to 2017 school year. Three themes emerged from the data: (1) support of fluid gender expression, yet not overt support; (2) passive marginalization of gender non-conforming or transgender identities or expressions; and (3) active marginalization of gender non-conforming or transgender identities or expressions. The "LGBTQ+ Dress Code Analysis Tool" was developed for policy makers to use to analyze their dress codes.