This study investigated the cognitive and affective student learning outcomes of 16 semesters of a mastery learning approach in teaching high school Business and Distributive Education classes. The class handout describing mastery learning, teacher and student responsibilities, examinations, grading procedures, 5-day unit activities schedule, information sources, and learning styles are presented. Study results support the hypothesis that mastery learning produces successful learning experiences for at least 80 percent of the students. Over 90 percent of the students received a course grade of A (indicating scores of at least 90 percent on every unit examination). On an anonymous teacher/course evaluation 96 percent of the students rated their total learning as high. Mastery learning requires an extraordinary investment in teacher time for preparation and grading, but is very rewarding. All students can and will learn if: (1) they know what is expected of them; (2) they are taught in the learning style best suited to them, (3) they are given the individualized corrections needed to alleviate previous learning errors; and (4) they can be retested to demonstrate mastery of objectives. Educators must look at themselves and their methods before assuming that some students cannot be successful. (BS)