A series of studies was conducted over a three-year period to determine whether the teaching technique developed in the 1960s called "inquiry training" is effective for teaching problem-solving, thinking, and/or decision-making skills. (Inquiry training is a process in which students are provided with a puzzling situation, are given the opportunity to gather information, and are then encouraged to formulate theories explaining the discrepant event.) The first year's study, involving students from grades 3 through 6, resulted in a change in the name of the technique to "cognitive enhancement," the refinement of teaching techniques used, and the development of a list of 19 cognitive enhancement skills. The second year's study involved students from grades 3 through 7 and showed statistically significant growth among students from pretest to posttest, while the third year's study resulted in a refinement of the testing methodology. It was concluded that cognitive enhancement (1) is a potentially highly effective method of teaching cognitive skills, (2) appears to be appropriate for use with elementary level to college level students, and (3) can be used with almost any subject matter. (A chart of subsets of cognition enhancement skills, a diagram of the relationships among sets of subskills, and information on ordering detailed results of each study from the author are included.) (LLZ)