This chapter examines violence carried out by young men and boys, its prevalence, contributing factors and cultural norms. It highlights how societal expectations and constructs of masculinity drive harmful behaviours and stresses the need for proactive approaches to prevent violence, such as early intervention, education and reshaping gender norms. The discussion demonstrates the detrimental impact on all young people. Current UK initiatives and research are reviewed, alongside interdisciplinary perspectives on gender. The chapter calls for cultural change, linking online and offline influences and outlining strategies to engage boys and evolve perspectives on masculinity to reduce violence.