This study assessed the implementation and perceived effectiveness of Comprehensive Sexuality Education (CSE) in secondary schools within Mpongwe District, Zambia. Employing a qualitative descriptive survey design, data were collected through questionnaires and semi-structured interviews from a purposive sample of 10 respondents, comprising biology teachers and headteachers across three schools. The findings reveal a significant gap between national policy and local practice. While educators expressed overwhelmingly favourable perceptions towards CSE and endorsed a comprehensive curriculum, its implementation was found to be inconsistent, under-resourced, and marginalised within the existing syllabus. Key barriers identified include a critical lack of specialized teacher training, a scarcity of instructional materials, and educators’ personal discomfort in delivering sensitive content. The study concludes that the primary obstacle to effective CSE is not educator opposition but a systemic failure in capacity building and support. It recommends a fundamental curriculum reform to establish CSE as a standalone, timetabled subject; the urgent scaling-up of continuous, practical teacher training; and the development of a reinforced national policy supported by community engagement to ensure standardised, effective, and culturally responsive implementation.