The language of co-creation has become popular with policy makers, researchers and consultants wanting to support evidence-based change. However, there is little agreement about what features a research or consultancy project must have for peers to recognise the project as co-creative, and therefore for it to contribute to the growing body of practice and theory under that heading. This means that scholars and practitioners do not have a shared basis for critical reflection, improving practice and debating ethics, legitimacy and quality.