The purpose of this paper is to report the results of a comparative and descriptive study that examined the relationship and effects of incorporating students' learning styles in the design of instruction and the outcome of students' learning, including their attitude and satisfaction. The paper will first explain how the literature on learning styles was used to develop a list of assumptions about learning styles, and further how these assumptions were used to identify a learning style model. It will also provide a detailed description of the process of using the learning style model to design and develop multiple instructional materials for two units of instruction for an online course. Finally, the paper will report the effects of this approach on students' learning and their perception, attitude and satisfaction in comparison with instructional materials that are designed and developed on the basis of the content and objectives, without incorporating students' different learning styles. (Contains 11 tables and 2 figures.)