Taking up the challenge of how to support social justice agendas by means of ethnographic research, I illustrate how a social movement’s own practices can be a source of emergent social theory. In response to challenge by indigenous Māori groups about oppressive colonisation in Aotearoa New Zealand, members of the Pākehā coloniser group embarked on their own decolonisation work. Focusing on the treaty for settlement, the Treaty education movement has undertaken three decades of conscientising education with Pākehā. To build a research method suitable for exploring the movement’s praxis, I was guided by the ethics and working practices of the Treaty educators, such as using visual imagery and group brainstorms. Following movement ethics of collective authorship and accountability, we developed a method of co-creating ‘visual theories’ of decolonisation for a coloniser group. I conclude that an ethnographer using effective means to record a social movement’s theorising may provide new resources for activists, educators, researchers, and public discourse. Finally, I offer a methodological recipe to encourage researchers to adapt ethnographic methods in creative and accountable ways towards advocacy and social justice ends.