Gender-based violence (GBV) in Papua New Guinea (PNG) is rife and strategies to reduce or prevent it have failed. This paper presents the views of 50 service providers who offer a unique vantage point to understand why GBV is so prevalent, through their work with victims, perpetrators, and their communities. Reflexive thematic analysis identified three key reasons for the prevalence of GBV: (1) Gender inequitable roles and norms (Big man and good woman), (2) Cultural practices and behaviours (Bride price and polygyny), and (3) Changing society (Erosion of traditional systems of governance and Technology). By presenting these key reasons, this study has also identified areas to target in awareness campaigns, education, and training to reduce and prevent GBV. The paper concludes that service providers would be a welcome resource in designing and developing culturally appropriate training and other interventions within their communities.