This paper examines student characteristics associated with success in a mastery learning strategy by: (1) continually assessing over terms the entry and exit skills of the students enrolled and (2) constructing and validating a scale for measurement in the affective domain. The mastery learning theory itself was proposed by Bloom (1968) as a method of individualized instruction. Subjects for the study were graduate and undergraduate students in educational psychology who progressed through a series of six units requiring mastery tests upon completion. While preassessment data showed substantial individual differences among students' knowledge of educational psychology, mastery learning theory suggests that such student differences may simply mean that different amounts of time are required to learn a task. Analysis of the data reveals that males generally reacted more favorably than females to the mastery learning technique and also that graduate students, who were primarily practicing teachers, rated the course less favorably than did undergraduate students. (Author/SES)