This paper discusses the Supplemental Instruction (SI) model of student academic assistance, a program recognized as exemplary by the U.S. Department of Education and developed at the University of Missouri-Kansas City (UMKC) to help students in difficult postsecondary courses master course content while they acquire and integrate effective learning and study strategies. The SI program is used by faculty who teach what have been identified as high-risk or historically difficult courses, assigning an SI leader to a course to provide three to five out- of-class SI lessons per week. SI leaders are usually course-competent students or learning center staff who have been trained in proactive learning and study strategies. The paper reviews research on the effectiveness of the SI program, discusses the specific features and activities of the program, and program costs. It also reports on the results of six studies at UMKC and other institutions to gauge the effectiveness of SI programs. Results of these studies indicated that course grades, reenrollment rates, and graduation rates were positively impacted by the SI program across racial and ethnic lines, as well as previous levels of academic achievement. (Contains 33 references.) (MDM)