Mastery learning is a group-based, teacher-paced instructional strategy. Because it is also committed to criterion-referenced evaluation and to a strong emphasis on feedback and correctives throughout the learning experience, it is often confused with competency-based education, individualized instruction, and related innovations. Mastery learning depends on five basic components: formal specification of cognitive objectives, division of course content and objectives into instructional units, formative/diagnostic evaluation, corrective or remedial instruction, and criterion-referenced summative evaluation. A review of the research reveals that mastery learning significantly improves student acquisition of cognitive skills and reduces the variability in achievement within the group. Increased retention and transfer of learning and student attitudes are also indicated. Teachers and administrators using mastery learning strategies find the planning process demanding and recommend developing the process a unit at a time. This document discusses the theory, techniques, and implementation of mastery learning strategy; reviews the relevant literature; and discusses two programs in which the strategy has proved successful: the Chicago Mastery Learning Reading Program and the Camden, South Carolina, Mastery Learning in Social Studies Project. A substantial reference section and an extensive appendix (including sample units from the Chicago program) conclude the document. (Author/PD)