Developing and evaluating scientific knowledge and its value requires a clear – or at least not too unclear – understanding of what ‘theory’ means. We argue that common definitions of theory are too restrictive, as they do not acknowledge the existence of multiple kinds of scientific knowledge, but largely recognize only one kind as ‘theory’, namely explanatory knowledge. We elaborate a typology that broadens and clarifies the meaning of ‘theory’. Consisting of five basic theory types – explaining, comprehending, ordering, enacting and provoking theories – the typology offers a framework that enables researchers to develop and assess knowledge in more varied ways and for a broader set of purposes than is typically recognized, as well as pro...