This paper describes a quantitative cost effectiveness model for Web-supported academic instruction. The model was designed for Web-supported instruction (rather than distance learning only) characterizing most of the traditional higher education institutions. It is based on empirical data (Web logs) of students' and instructors' usage implementing Web-mining techniques. This will enable to quantify the costs and benefits of Web-supported instruction on both the single-course and the campus-wide levels. This paper describes the model's characteristics; the costs and benefits components in six dimensions; the computational mechanism that translates the cost and benefit components into quantitative values referring to university policymakers, instructors, and students; and its development process consists of the model design, creation of the computational mechanism and validation by instructors and students. (Contains 2 tables and 2 figures.)