Development practice is informed by theories of change, but individuals and organisations may not make them explicit. Practitioners may be unaware of the extent to which strategic choices and debates are informed by disparate thinking about how history happens and the role of purposeful intervention for progressive social change. In the past few years, some Oxfam GB staff have been creating processes to debate their theories of change as part of an effort to improve practice. In this context, the authors introduce four sets of ideas about change, with a discussion of how they have been explored in two instances, and some of the challenges emerging from this process. Through explicitly debating theories of change, organisational decision-making processes can be better informed and strategic choices made more transparent.