Mastery learning is an optimistic theory of human learning that proposes that all learners can achieve mastery of the school's curricular content. Since it demands long range planning and precise designing of learning programs, this method cannot be employed without a great deal of thought and preparation. The forerunners of mastery learning go back as far as the seventeenth century, but the modern concept originated with a model developed by John B. Carroll in 1963. According to Carroll's theory, if students are normally distributed according to aptitude, and, if all are given the same instruction, achievement will be normally distributed. The method assumes that all children can learn equally or nearly equally most school tasks. The mastery learning model consists of six components: (1) identification of specific objectives for each learning task; (2) preassessment of the learner; (3) instruction; (4) diagnostic assessment; (5) prescription; and (6) postassessment. Areas of this approach which should be further examined include: the need for highly specified instructional goals, the philosophical disagreement over the concept of equal education, and limited teacher skills for using mastery learning. However, mastery learning is an innovative method and a powerful concept which deserves careful consideration. (FG)