This article is a methodological commentary on Eells’ (2010) summary of his research on case formulation. It draws attention to an epistemological tension between a positivist and a qualitative/hermeneutic paradigm. I argue that the kinds of questions researchers are most concerned with in the field of case formulation are ones with direct relevance for practice and that an exclusively positivist paradigm is problematically suited to answer these, an observation that emerges from a consideration of Eells account of his research. While Eells’ account of his case-based strategy is initially positivist in intent, the introduction of a hermeneutic approach opens the field up considerably. I conclude (a) that a "mixed methods" paradigm, which integratively and rigorously combines quantitative and qualitative methods and which has recently been called a "third research paradigm," offers a particularly attractive epistemological framework for planning research on case formulation that can directly guide and improve practice; and, following from this point, (b) that the meaning and direction of Eells' research can be enhanced by explicitly conceptualizing it within such a mixed methods paradigm.