The intricacies that negotiate human sexuality and sex-negativity customary in school-based sexuality education programs in the United States contribute to sex-negative notions that inform current models of sexuality education as heteronormative and cisnormative, which assumes all students are heterosexual and cisgender. This fact essentially ignores and erases transgender, gender diverse, and nonheterosexual identities. The research questions addressed in this dissertation are as follows: RQ1: What does the history of school-based sexuality education tell us about transgender issues at the high school level in the United States? RQ2: What are principals' perspectives regarding sexuality education curricula in Hawaii public high schools? RQ3: What are principals' perspectives regarding inclusive services offered to transgender students in Hawaii public high schools? This mixed-methods study used historical sources to address the first of three research questions. The second and third research questions collected qualitative data gathered via semistructured interviews of Hawaii high school principals that were analyzed following Braun and Clarke's (2006) six-step, inductive thematic procedure. Findings suggest that both abstinence-only education (AOE) and comprehensive sexuality education (CSE) are problematic and discriminatory. Hawaii high school principals perceived the following: (a) holistic sexuality education (HSE) is likely beneficial for students but may be met with controversy by conservative stakeholders, (b) multiple stakeholders influence sexuality education curricula in Hawaii public schools, (c) honoring transgender students' identities and preferences is essential, and (d) training for faculty and staff in transgender sensitivity is effective and needed. The study's findings support an argument for holistic sexuality and gender education as a promising model for future implementation of K-12 sexuality education, intended to positively impact marginalized transgender students. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]