In comparing two methods of instruction, one must be cautious about forming conclusions because of certain variables which can influence results. Such variables are differences in populations, in instructor effectiveness, and in availability of instructional aids. The comparison does, however, demonstrate differences between the two groups. The fact that the entire class taught by the modified course passed the proficiency examination after nine trials, compared to 12 for those from the traditional course, is not in itself significant. The impressive fact is that in the early trials the rate of students who qualified for clinical practice was nearly doubled in the learning theory group. This might imply that the learning theory group demonstrated a greater degree of problem-solving ability because of opportunities for discovery learning within the course. Since both classes were given the proficiency examination approximately two-and-a-half months after they had completed the preclinical course, it would seem that the learning theory design resulted in retention of the objectives of the course by a significant number of students. Consequently, it is the authors' opinion that the learning theory design provided a more effective method of instruction. Clinical operative dentistry consists of highly intricate procedures which for their successful completion require complex psychomotor responses in the operator. Therefore a program of instruction in operative dentistry must be highly effective. When such a program is organized, utilization of learning theory principles, especially those of skill learning, may aid in achieving this goal.