This article presents a methodological approach to educational psychology research in which researchers engage in collaborative transformations of educational practice while developing theory concerning the societal and scientific relevance of these transformative processes. The theoretical inspiration for this approach stems from German-Scandinavian Critical Psychology, Transformative Activist Stance, and the Change Laboratory Framework -- three research traditions with common roots in cultural-historical psychology and activity theory. Empirically, the article is based on a transformative research collaboration between the author and a 2nd grade teacher at a Danish municipal primary school. The aim was to develop an intervention framework to support the development of cultures of care within communities of children, while simultaneously producing theoretical knowledge about the conditions that enable the development of such cultures within the contradictory and dilemma-filled historical and socio-political context of Danish municipally governed schools. Empirical excerpts show how a novel intervention principle emerged as a synthesis of the researcher and the schoolteacher's respective, seemingly contradictory knowledge contributions. Against a backdrop of historical-institutional analyses, it is argued that this intervention principle represents a novel scope of possibilities for educational professionals struggling to manoeuvre within the various contradictions and common problems inherent to Danish municipally governed schools. In the discussion, it is argued that the transformative approach presented here seems particularly promising for the democratisation of knowledge production. This assertion is supported by a demonstration of how the approach is particularly flexible to continuously integrate critique, contributions, and contestations from co-researchers within educational practice, adults as well as children.