Teachers and authors of guides to student writing, particularly writing of an informative or argumentative genre, stress the importance of the introductory and concluding sections in an essay. Within a discourse-processing framework, introductions and conclusions represent rhetorical structures that affect comprehension of the text. However, there is little documented empirical evidence of how, and to what degree, the introduction and conclusion affect the grade given to an essay. In this experimental study, undergraduate students graded essays in which the quality of the introduction or conclusion was varied while the main body of the essay remained intact. The quality of the introduction had a greater effect on the grade awarded than did the quality of the conclusion.