A persisting gap in the field of disciplinary literacy is lack of conceptual clarity around the term "discipline." In this theoretical article, the author explains some concerns with existing definitional imprecision and argues that genre-oriented activity theory offers a way to reconceptualize the focus of disciplinary literacy, especially in relation to academic, professional, and other literacies. The author provides an overview of Rhetorical Genre Studies, focusing on a genre-oriented activity theory model from David Russell, to demonstrate how genres within activity might be used to productively reframe some of the scholarship of disciplinary literacies. Specifically, the notion of genres as recurrent mediating tools used within multilayered, laminated activity systems may offer a more complex frame for exploring disciplinary literacies. The author offers a brief review of previous disciplinary literacy research to show how the field might benefit by incorporating a genre-oriented approach and closes with research questions for future study.