Faculty often wish to devote time and resources to improve a course to be more in line with principles of how people learn but are not sure of the best path to follow. We present our tested approach to research-based course transformation, including development of learning goals, instructional materials based on student difficulties, and assessment to see whether the approach worked. This method of course transformation has measurably improved student learning in several courses, and we present one such course as a case study--an upper-division physics course. We relied on various support personnel, including undergraduates, to help instigate and maintain the course transformations, and we describe the departmental and institutional factors that are important for successful transformation and sustainability. This model, and the lessons we have learned through its implementation, may serve as a guide for faculty interested in trying a new approach in their own courses. (Contains 2 figures and 2 tables.)