Questions frequently arise about the origins of outcome-based education and mastery learning, their similarities and differences, their theoretical and practical links, and evidence about their effects on student learning. Historical and theoretical perspectives show a clear distinction between outcome-based education and mastery learning. Outcome-based education is principally a curriculum reform model with definite implications for the assessment of student learning. Mastery learning, while known by various names and in various forms, is principally an instructional strategy labeled by B. S. Bloom, and designed to help teachers enhance the quality of their teaching procedures so that more of their students learn excellently. Outcome-based education and mastery learning address different educational concerns, but their potential if used in combination is clear. The combination of a thoughtful curriculum and effective instructional practices makes true improvement in learning possible. One figure illustrates the discussion. (Contains 27 references.) (SLD)