Teachers' engagement with and understanding of educational research and data is an increasing concern for policy-makers around the globe. With unprecedented access to, and new forms of, 'data' in schools, concerns for its 'best practice' use in classroom decision-making have come to the fore. In academic spaces, these developments have also been of concern due to what such pushes for 'evidence-based practice' may elide in terms of teacher knowledge and professionalism. In this article, we present findings from two national contexts, England and Australia, in order to explore how teachers understand themselves and their work in relation to educational data and research. We find that, despite highly engaged samples across contexts who place considerable importance on such research and data, respondents do not report an equal sense of capacity across the various forms which they may take. Particular limitations are identified in relation to action research. We argue that these results have consequences for the development of a 'mature' profession that goes beyond performative forms of professionalism and towards those of a 'research-rich' culture of trust.