Introduction <p>The present study examined elementary and secondary school teachers’ perceptions of support for gender- and sexual-diversity–inclusive school practices, perceived obstacles, and confidence in implementing such practices. Additionally, the study explored the role of demographic (gender, age) and occupational characteristics (years of teaching experience, educational level) in shaping these perceptions.</p> Method <p>A total of 455 public school teachers (79.1% women), employed in elementary (66.7%) and secondary education (33.3%) during the 2024–2025 academic year, completed self-report measures assessing perceived school practices, barriers, and confidence regarding gender- and sexual-diversity–inclusive education.</p> Results <p>Findings indicated that elementary school teachers expressed lower support for gender- and sexual-diversity–inclusive school practices but reported fewer perceived obstacles compared to secondary school teachers. Moreover, within elementary education, male teachers, those with fewer years of experience, and those holding lower educational qualifications demonstrated less support and greater perceived barriers toward implementing inclusive practices. In contrast, among secondary school teachers, demographic and occupational variables did not significantly differentiate their views.</p> Conclusion <p>Τhese findings underscore that teachers’ perceptions of the educational inclusion of students with gender- and sexuality diversity are shaped by educational level and individual background factors, highlighting the importance of contextualized interpretations of inclusivity readiness across different teaching groups.</p> Social-Policy Implications <p>Educational policies and training initiatives should be tailored across educational levels, accounting for teachers’ distinct demographic and professional profiles, to promote consistent and effective implementation of gender- and sexual-diversity–inclusive practices in schools.</p>