The purpose of this project was to produce materials that would foster favorable teacher attitudes toward the philosophy behind mastery learning. One other purpose was to help teachers acquire the skills needed to use mastery learning in their classrooms and to determine the effects on pupils when mastery learning techniques were used. Forty-four teachers and interns from four Indianapolis schools were equally divided into groups according to race and sex. The material developed was a Mastery Teaching module which included an introduction and six sections. A slide/tape accompanied each of the seven parts. An accompanying manual contained objectives, practice exercises, and feedback. The manual also included self-tests with answers for each section, a pre-test on prerequisites, and a project section. Pre- and post-treatment measures were administered to the teachers and interns on both cognitive and affective variables. The results indicated that teachers and interns acquired the mastery teaching skills and used them to the degree that pupils perceived differences in their teaching. Teacher attitudes toward the mastery teaching philosophy were generally positive, and students' attitudes and achievement were favorably altered because of their teachers' use of mastery teaching. (DT)