In this paper I discuss the use of genre as a theoretical construct in academic writing instruction in the context of English for Academic Purposes (EAP) courses. I begin by considering the notion of discourse competence as a concept that accounts for the knowledge elements and skills employed by expert academic writers, and then consider genre as a way of operationalizing the different elements of discourse competence knowledge for the purpose of writing instruction. I review briefly the diversity of approaches to theorizing genre knowledge, and then present the dual social genre/cognitive genre approach that I have used as a basis for research and course design in an EAP context. I exemplify this model by summarizing the key elements of two studies of research genres in which I have used this model. I conclude with a brief theoretical discussion of the issue of construct validity in relation to using the concept of genre in research that relates to writing instruction.