Comprehensive sexuality education (CSE) is essential in empowering adolescents with the knowledge and confidence to manage their sexual and reproductive health. Despite its recognized benefits, access to quality CSE remains limited, especially in low-income countries, where societal norms and structural barriers hinder effective delivery. The aim of this study is to investigate the experiences and perceptions among students, teachers, and principals in Nepal about comprehensive sexuality education. Qualitative methods were used. 13 Semi-structured interviews and 1 focus group discussion were carried out with 15 teachers and principals working at higher secondary schools and two focus group discussions were conducted with a total of 13 adolescents. Thematic analysis was used to analyze the data. Four themes were developed: Resistance to Teaching and Learning, Preparation and Engagement Strategies, Taboos and Silencing and Structural Barriers. Students, teachers, principals and students reported discomfort and embarrassment when discussing sensitive topics, with gender dynamics playing a significant role. Strategies like warm-up sessions and continuous interaction with students and parents were used to create a supportive learning environment. However, socio-cultural barriers and family attitudes continued to hinder open discussions about sexuality. Structural barriers, including the lack of formal training for teachers and inadequate instructional materials, further impeded effective CSE delivery. The experiences of CSE in Nepal among students, teachers and principals highlight significant barriers including cultural taboos, gender dynamics and insufficient resources. Addressing these barriers through comprehensive teacher training, curriculum reform, and societal engagement is critical to ensure access to CSE.