We start this article from Gilbert Ryle’s distinction between propositional knowledge, ‘knowing-that’, and procedural knowledge, ‘knowing-how’, and investigate how participants in interaction display orientation to the latter in various settings. As the knowledge of how things are done, know-how can be analyzed in terms of its relevance and consequentiality for parties in interaction. Similarly, as participants adjust their actions and understandings according to their sense of what they know and assume others to know, their know-how and its distribution may form (...) the basis for adjusting and reshaping their actions, forms of participation and identities. In this sense, we aim at opening an investigation of know-how, and its conventionalized form, expertise, in interaction. In as much as it forms a distinct domain, a new research object – expertise in interaction – is formulated. Methodological issues of how to study expertise in interaction are discussed. The data are in English and Finnish. (shrink)