The theoretical literature to support good research practice, either action research or science, appears to lack practical guidelines for conducting systematic inquiry, within the contingencies of a given research context. I suggest this lack is due to some misconceptions about the nature of good research. In order to re-dress this lack and to enhance the practices of both methods of inquiry, I wish to challenge what I believe to be some wrong assumptions about good research. I will base my challenge on the empirical evidence of 22 case studies of acknowledged good research in both action research and agricultural science and on the understanding of knowledge as defined by the philosophical sceptics, ie that the ideal of ‘true and certain knowledge’ is unattainable. The assumptions about good research that I wish to challenge are: that there is one scientific or action research method, that prescriptive theoretical literature provides a basis for sound practice, that research is a search for truth, that participation is the defining feature of action research and that action research and science are incommensurable. On the basis of my argument that action research and science are not incommensurable, I will suggest guidelines for the practice of rigorous systematic inquiry which are relevant to both methodologies. If those guidelines are acceptable to all researchers, they can provide a basis for collaborative research between action researchers and scientists which can improve the quality of research results for clients. Such collaboration can also improve the practice of the researchers by enabling them to learn methods of systematic inquiry from each other’s processes. I will demonstrate an application of these guidelines with a case study of a collaborative and participative research project conducted by myself and an agricultural scientist colleague.