The CDIO Initiative is a community for engineering education development, but since 2016 its annual conference also calls for research. This paper considers possible roles for CDIO in the field of engineering education research (EER). The EER landscape is explored, in particular considering whether the aim of research is to seek knowledge to improve engineering education, or to seek knowledge for its own sake? Although usefulness and scholarliness are not mutually exclusive, the priority matters throughout the research process and in evaluating work. Introducing concepts from similar debates, this paper argues for embracing the tension, to form a productive relationship between scholarliness and usefulness. A dual objective is implied: usefully contributing to the improvement of engineering education and establishing a recognised research field enabling sustainable careers for researchers. Quality mechanisms are necessary for staking out borders and upholding standards, at least to weed out work that is neither scholarly nor useful.