Many studies have underlined the high prevalence of child marriage in Ethiopia, particularly in the Amhara region, and their devastating effects on the mental and physical health of the girls involved. This qualitative research aims to investigate the effectiveness of multimedia messaging - including radio and print messaging, face-to-face group discussions as well as interactions with a radio station - in altering people's perception of child marriage. By analysing reflection statements in group diaries, the study identifies changes in the Knowledge, Attitude and Practices (KAPs) concerning child marriage of a multimedia audience in three districts of the North Gondar Zone in the Amhara region. The study contains a comprehensive literature review, comprising several findings regarding the magnitude of child marriage practices. Using the hybrid qualitative method of thematic analysis, it highlights important features and drawbacks of potential approaches to mobilising the community against child marriage. Moreover, a detailed description of multimedia intervention procedures is included, which can serve as a guideline for media practitioners and social development initiatives.