This article explores relationships between activity theoretic and ethnomethodological studies of work and its objects, with specific reference to the case of design practices in civil engineering. My starting point is the shared interest of activity theory and ethnomethodology in the place of artifacts in everyday working practice. I review briefly some basic premises of first ethnomethodological, then activity theoretic studies of artifacts-in-use. I then offer a preliminary account of computer-aided and paper-based design work in civil engineering, informed by both perspectives. My account emphasizes the multiplicity of media and associated objects involved in the work of engineering on the one hand, and their integration in practice into a coherent field of action on the other. The article concludes by returning to the question of relationships between ethnomethodology and activity theory, focusing on differences in their respective stances toward theory itself.