The difficulties faced by EFL/ESL students when asked to pro duce a piece of writing are often due to an inadequate understanding of how texts are organized. To facilitate effective writing therefore, teachers have to familiarize students with the rhetorical structures which are an important part of the meanings of texts.This article focuses on an important type of written discourse, the argumentive essay, and proposes a preliminary descriptive frame work of its rhetorical structure. Presenting research results, the author shows that a "categories analysis" can clarify the structure of written texts and provide pedagogically useful materials. A case is argued for the importance of explicit linguistic knowledge in deve loping writing skills and some implications for teaching strategies are drawn.