This study investigated the cognitive and affective student learning outcomes of 36 semesters (equivalent to 18 years) using the mastery learning approach in high school distributive education classes (n=7,179 students). Student achievement in the cognitive area is reported by increasing grade point averages, and test scores are presented to show the consistent high level of academic achievement of students. Affective information (attitudes toward school and learning) has also been elicited from the entire sample and is presented to show positive changes. Additionally, more recent information regarding students' (n=843) learning styles and the use of those styles to facilitate learning is reported. This investigation provides information regarding the effectiveness of mastery learning in real world classroom experience. An appendix summarizes mastery learning and teaching strategy. (Contains four references.) (Author/SLD)