It is proposed that the only technology that has consistently been effective over traditional education approaches is the personalized system of instruction (PSI). An overview is given of the purpose, origin, development, and use of the system. The five critical components are outlined: use of student assistants, emphasis on the written word in student-teacher communication, use of lectures and discussions as a means of inspiration and motivation rather than a source of critical information, the unit perfection requirement for advancement, and working at the student's own pace. Another essential feature is a set of detailed performance objectives. Research on the effectiveness of the method is reviewed. Problems in implementation are also addressed, and some recommendations are made, including future research needs. It is concluded that college instructors could improve their teaching by implementing PSI as a major teaching method, and that PSI provides colleges with one technology to bring about changes for more effective instruction. A list of references and a PSI flow chart are included. (MSE)