This paper describes the SCALE-UP project. The primary goal of the Student-Centered Activities for Large Enrollment University Physics (SCALE-UP) Project is to determine the best way to establish a highly collaborative, hands-on, computer-rich, interactive learning environment in large-enrollment physics courses. We know from extensive educational research that students should collaborate on interesting tasks and be actively involved with the material they are learning. The Physics Department at North Carolina State University has had considerable success with small classes taught this way and is now searching for the best way to "scale-up" the innovations so that students taking our large enrollment engineering physics courses can benefit. We are folding together lecture and lab with multiple instructors in a way that should provide an economical alternative to traditional lecture-oriented instruction. The project involves the development, evaluation, and dissemination of new curricular materials that will support this type of learning. The SCALE-UP Project has the potential to radically change the way physics is taught at large colleges and universities. The pedagogical techniques should be general enough to encourage similar reforms in other science, engineering, and mathematics classes.