Background: Men's perpetration of intimate partner violence (IPV) limits gains in health and wellbeing for populations globally. Largely informal, rapidly expanding peri-urban settlements, with limited basic services such as electricity, have high prevalence rates of IPV. Evidence on how to reduce men's perpetration, change social norms and patriarchal attitudes within these settings is limited. Our cluster randomised controlled trial aimed to determine the effectiveness of the Sonke CHANGE intervention in reducing use of sexual and/or physical IPV and severity of perpetration by men aged 18-40 years over 2 years. Methodology: The theory-based intervention delivered activities to bolster community action, including door-to-door discussions, workshops, drawing on the CHANGE curriculum, and deploying community action teams over 18 months. In 2016 and 2018, we collected data from a cohort of men, recruited from 18 clusters; nine were randomised to receive the intervention, while the nine control clusters received no intervention. A self-administered questionnaire, using audio-computer assisted software, asked about sociodemographics, gender attitudes, mental health, and the use and severity of IPV. We conducted an intention-to-treat analysis at the cluster level comparing the expected risk to observed risk of using IPV while controlling for baseline characteristics. A secondary analysis used latent classes (LCA) of men to see whether there were differential effects of the intervention for subgroups of men.