Aptitude tests are defined in contrast to intelligence and achievement tests. Although aptitude tests, like intelligence tests, measure a student's overall performance across a broad range of mental capabilities, the former also often include items that measure more specialized abilities (such as verbal and numerical skills) that predict scholastic performance in educational programs. Compared to achievement tests, aptitude tests cover a broader area and a wider range of experiences. Research data indicate that individually administered aptitude tests identify predictors of future scholastic achievement, compare performance across students, provide a profile of students' strengths and weaknesses, assess differences among individuals, identify hidden talents in some children, and provide information about handicapped students. Aptitude tests provide information for instructional, administrative, and guidance purposes. Overall, research on the improvement of aptitude test scores is inconclusive, but it does indicate that effective training approaches involve the following: longitudinal, non-intrusive techniques; interaction of student abilities and training methods; practice and feedback; incorporating other strengths of the student; and focus on aspects of intellectual aptitude that have been identified as trainable. A five-item list of additional reading materials is included. (TJH)