The problem of this study was to determine whether Kenyan Bible college students who receive instruction using a modified (highly structured) mastery learning model will demonstrate greater achievement in knowledge of Christian Church history as compared to Kenyan Bible college students who receive instruction using a traditional (minimally structured) non-mastery learning model. The subjects were 17 second-year Kenyan Bible college students enrolled in a course on Christian Church history, and they were randomly assigned to the two treatment conditions. The researcher served as instructor for both groups. The experimental group used a textbook, detailed syllabus, 200 page study guide (featuring an advance organizer to provide an ideational scaffolding), and a lesson-development feature (providing an enabling objective, congruent questions, and informative feedback for each lesson segment). The control group used a textbook and a less-detailed syllabus. Both groups shared the same classroom lectures, class discussions, required assignments, examinations, and review of examination items. Five tests of Christian church history were administered, including a pretest, three unit tests, and a comprehensive course examination. Test data were analyzed using a 2 x 5 (treatment x testing occasion) repeated measures analysis of variance (RM ANOVA). The percentage of students performing at mastery level (80% …