The Competency-Based Instruction (CBI) system has been used to teach physics for more than 20 years in the Michigan State University Physics Department. In this approach, traditional lectures have been replaced by a learning environment that contains a variety of instructional aids, including written materials, computer-assisted instruction, and interactions with a consultant. The CBI system allows students to adjust their pace through the course, moving nearly as quickly as they are able, with constant feedback to the student on his or her progress.I have used an adapted version of the CBI system for use in the Physical Optics and Photometry course of the University of Missouri-St. Louis, School of Optometry for four years. This article will describe the mechanics of the system and discuss experiences with it.