Mastery learning refers to the idea that teaching should organize learning through ordered steps. In order to move to the next step, students have to master the prerequisite step. Mastery learning engages the learner in multiple instructional methods, learning levels and multiple cognitive thinking types. Traditional instruction holds time constant and allows achievement to vary within a group of students. A college course may last sixteen weeks, for example, and at the end of that time students who have mastered the subject thoroughly receive grades of A, those who have mastered very little get grades of F, and so on. Mastery learning, on the other hand, holds achievement constant and lets the time students spend in pursuit of the objectives vary. In the same college course, a few students might meet the standards in ten weeks; most might meet the standards in sixteen weeks; but a few students might take twenty–five or thirty weeks to meet these standards.This paper highlights principles,steps,design application of mastry learning etc.