‘Urban internally displaced persons’ is a contested category in Uganda. Both international and national definitions of Internally Displaced Persons (IDPs) include, in principle, persons displaced by conflict and dwelling in urban areas. However, existing assistance and protection practices have transformed the IDP label, effectively restricting its application to people residing in IDP camps. Displaced people living in urban areas are perceived either as economic migrants or as former IDPs who have reached a durable solution. This article analyses the process, outcomes and challenges of a collaborative research project between forced migrants, the Refugee Law Project (a national organization), and researchers from the Norwegian University of Science and Technology (NTNU). The joint goal of the researchers and urban IDP representatives in the research project was to promote the inclusion of urban IDPs in the IDP label by revealing the political and bureaucratic institutional agency at work in the processes of labelling. This article seeks to demonstrate how such collaborative action research may lead to strengthening the knowledge base regarding forced migration in urban areas, mobilizing communities for advocacy, and influencing the formation of humanitarian categories.