Understanding students' learning styles is one of the first steps to providing an effective education. Four elements must be present in schools for mastery of content to occur. These four elements operate in sequence and each supports those that follow. The elements are (1) diagnosis of student traits and skills, (2) development of specific educational plans for students, (3) application of appropriate instructional strategies and methodologies, and (4) evaluation of student achievement, teacher performance, and program quality. Recent educational reform efforts have devoted considerable attention to the last three of these four steps but have tended to ignore diagnosis, the critical first step. Drawing on the learning style research of Rita Dunn, the National Association of Secondary School Principals' Learning Style Task Force developed, tested, and refined the Learning Style Profile, an easily administered, 23-scale instrument for assessing the stylistic skills and preferences of students in middle and high schools. The factors assessed include cognitive skills, perceptual responses, study preferences, and instructional preferences. (PGD)