: This research aimed to build a program based on pragmatic theory, and measure its effectiveness in developing expository writing skills among middle school students. The problem of this research was identified in the weakness of expository writing skills among middle school students, and the lack of programs based on modern theories to develop these skills, such as pragmatic theory. To reach a solution to this problem, this research followed a set of steps, perhaps the most important of which are: building a list of expository writing skills appropriate for first-year middle school students, defining the foundations for building a program based on pragmatic theory, and defining its components represented in its goals, content, teaching, activities, and media. Evaluating it, and measuring its effectiveness in developing expository writing skills among first-year middle school students, through constructing and controlling an expository writing test, selecting two groups of first-year middle school students, and applying the test to them beforehand, then applying the program based on pragmatic theory to this group, and applying the test to them. Afterward. The research reached a set of results, perhaps the most important of which is: the effectiveness of the program based on pragmatic theory in developing expository writing skills among the experimental group of first-year middle school students. Keywords: program - pragmatic theory - expository writing