In this article we discuss the motivation for and role of theory in management accounting. We argue that theories in an applied field such as management accounting research should provide explanations that are useful for those we study – managers, organizations and society. We evaluate the nature of theories currently used and developed. Those theories that are considered theories by the research community are largely imported from other disciplines, but have hardly anything that makes them unique to management accounting. Those theories that are not currently regarded as theories by many of our colleagues attempt to explain how to apply management accounting to achieve superior performance. We argue that both forms of theories, at present, largely fail to provide valid support for practitioners. We contend that management accounting theory should help us to answer questions of what kind of management accounting systems we should apply, how, in what circumstances, and how to change them. We provide suggestions on how management accounting research could proceed to produce better theories in this regard.