|Abstract||The purpose of this study is to show that paragraphs have a deep and a surface structure and that the amount of the deep structure of the paragraph that is mapped onto the surface is directly related to the mode of discourse. A paragraph has a surface structure that can be regarded as a base, and that base generates an abstract deep structure. This deep structure with its assumptions is a part of the semantic interpretation of the paragraph and is mapped onto the surface structure through the processes of ellipsis, subordination, and embedding. An effective analysis of discourse involves both a plane of content and a plane of expression. The associational references to ideas and images is designated here as deep structure. The subject matter organized into personal handwriting is equivalent to the surface structure. Each chapter analyzes the deep structure of paragraphs from one of James L. Kinneavy's classifications of discourse in A Theory of Discourse. The study is limited to reference discourse, with special sections for scientific, exploratory, and informative; expressive discourse; and persuasive discourse. Paragraphs were chosen at random, and they averaged about one hundred and fifty words. Tree diagrams were used to illustrate graphically the deep structure. Investigations of referential discourse paragraphs revealed that the deep structure of scientific paragraphs is relatively uncomplicated with few assumptions and little elliptical information. The audience is more of a concern in the informative paragraph than in the scientific paragraph, although the emphasis is still away from personal identification of the author and toward anonymity. Sometimes the deep structure of exploratory discourse is complex, sometimes quite simple. The writer makes certain assumptions in the course of the exploration that are based on his own previous understandings and depending upon the writer's conception of his audience, these assumptions will or will not be supported or mapped onto the surface. The deep structure of persuasive paragraphs is unusually complex, made up of both elliptical assumptions and information. The theory of deep structure of the paragraph has multiple uses in the composition class. Analyses of deep structure could be used to illustrate the following: 1. The necessity in persuasion of mapping a sufficient portion of the deep structure onto the surface structure to enhance the understanding of the reader. 2. An illustration of a particular writer's style. 3. An illustration of the economy of words which many writers use to suggest a broad world of invention. 4. An effective demonstration of the amount of information mapped onto the surface in the various types of referential discourse. Analyses of the deep structure of students' own paragraphs can also help them to hold onto their thoughts while developing and expanding an idea.