In fall 1980, a self-paced, individualized, mastery learning approach was adopted at Hibbing Community College for four chemistry courses in order to increase student performance and success and to provide scheduling flexibility for adult students with outside commitments. While both the traditional approach used prior to fall 1980 and the new approach relied primarily upon a lecture-laboratory format, there were certain testing and procedural differences. In the traditionally taught courses, students participated in eight or nine labs, which they completed once for a grade, and took in-class exams. Under the new approach, the number of labs was reduced to five to allow for more one-on-one interaction, students repeated the labs until they had performed them correctly, and students took exams on their own time. A comparison of grades and completion rates under the two instructional approaches reveals that student performance increased dramatically under the new instructional approach, but that course completion rates tended to be lower. Students who were enrolled in Chemistry 111 (Aspects of Chemistry) tended to have better grades and completion rates than those in Chemistry 124 (General Principles of Chemistry) in both the individualized and traditional classes. (HB)