Prison violence is a significant concern both in New Zealand and across the globe. While past theories and empirical research have highlighted several risk factors implicated in prison violence, we continue to have a limited understanding of what happens, and why it happens, during a prison violence event (PVE). Furthermore, we have even less of an understanding about the involvement of gangs in prison violence despite research suggesting that gang members are over-represented when it comes to involvement in such incidents. Previous research on gang violence in prison also focuses heavily on prisons in the United States of America which have different cultural, social, and judicial dimensions and may not generalise to the New Zealand prison population. This research project aimed to fill some of these gaps by taking an exploratory approach to induce new ideas following interviews with gang members who have first-hand experience with perpetrating prison violence. We used Grounded Theory to collect and analyse event descriptions to build a descriptive model of institutional gang violence which describes the distal and proximal features of the PVE process. The resulting model contributes to a better understanding of the function of PVEs involving gang members and the extent to which these events differ when carried out for or on behalf of the gang. It also highlights the role of past trauma and the prison ecology in the perpetuation of these events.