INTRODUCTION: Adolescent girls and young women aged 15 to 24 years have some of the highest HIV incidence rates globally, with girls two to four times more likely to be living with HIV than their male peers. High levels of intimate partner violence (IPV) experienced by this age group is a significant risk factor for HIV acquisition. While behavioural interventions to prevent IPV and HIV in southern Africa have seen some success in reducing self-reported experiences of IPV, these interventions have largely failed to achieve similar outcomes for young women. DISCUSSION: We identify three main reasons for the failure of IPV/HIV interventions for many young women in southern Africa. First, interventions are usually developed without the meaningful involvement of both young women and young men. Youth input into research design is largely focused on user testing or consultation of targeted groups, involving relatively low levels of participation. Second, interventions are focused on addressing individual risk factors rather than broader social and structural contexts of being a young woman. "Risk factor" interventions, rather than supporting women's agency, can pose a major barrier for supporting changes in behaviour among young women because they often fail to dislodge well-entrenched gender and age-related inequalities. Third, current intervention models have not adequately accounted for changes in gender norms and relationships across southern Africa. Individuals are getting married later in life (or not at all), new technologies are transforming romantic interactions and opening new opportunities for violence, and discussions about women's rights are both challenging gender inequalities and reinforcing them. CONCLUSIONS: In order to move beyond the status quo of current approaches, and to support real innovation, IPV/HIV prevention interventions need to be co-developed with youth as part of a meaningful participatory process of research, intervention design, youth involvement in development and implementation. This process of co-development needs to be radical and break with the current focus on adapting existing interventions to meet the needs of young people, which are not well understood and often do not directly reflect their priorities. Broader social contexts and compound lenses are needed to avoid narrow approaches and to accommodate evolving norms.