Advancing equity is a major challenge facing education systems globally. This creates an imperative for researchers to work with policymakers and practitioners to affect change. There have been many attempts to do this using various forms of action-oriented research and a considerable body of knowledge exists about their strengths and limitations. The paper describes the development of a methodological approach, Design-Based Equity Research (DBER), which draws on these existing traditions but is also distinct in its explicit consideration of values. It is marked out by a process of knowledge generation, in which researcher and practitioner knowledge meet, in context, to produce new knowledge about ways in which broad values of equity might be better realized in future practice. The paper explains how the approach was developed, conceptually and empirically, through a series of studies carried out over the last twenty years. It concludes that the process has the potential to generate two important types of knowledge: substantive knowledge about how equity can be realized in practice, and processual knowledge about the DBER process itself.