We define action research and relate it conceptually to other research strategies. The inadequacy of some action research methodologies for theory generation and testing is discussed. We describe the way we re-dressed this deficiency in our study of the journey from traditional nursing to patient-centered nursing. The differences and tensions between "research-thinking" and "practice-thinking" are explored and we show how our research partnership balances the two ways of thinking. We suggest that operating within the research criteria, presented here, may help action researchers to conduct rigorous research, as well as to improve practice.