THIS PAPER PRESENTS INDEFINITIVE APPROACHES FOR THE BEHAVIORAL ASSESSMENT OF PRESCHOOL CHILDREN. IT REVIEWS THE STATE OF THE ART OF BEHAVIOR MEASUREMENT OF PRESCHOOL CHILDREN AND SUGGESTS SOME NEW OR MODIFIED MEASURES. AN INTRODUCTORY OVERVIEW DISCUSSES REASONS FOR BEHAVIOR ASSESSMENT AND FACTORS WHICH AFFECT ANY BEHAVIORAL APPROACH. SOME PROCEDURAL CONSIDERATIONS AFFECTING ANY RESEARCH WITH PRESCHOOL CHILDREN ARE GIVEN. THESE CONSIDERATIONS DEAL PRIMARILY WITH DIFFICULTIES THAT CAN ARISE WITH THE PHYSICAL SETTING AND WITH INTERPERSONAL RELATIONSHIPS. MAJOR AREAS FOR BEHAVIOR ASSESSMENT ARE SURVEYED--(1) OBTAINING BACKGROUND AND ENVIRONMENTAL INFORMATION, (2) LEARNING, (3) SENSORI- AND PERCEPTUAL-MOTOR ACTIVITY, (4) LANGUAGE AND VERBAL BEHAVIOR, (5) ATTENTION AND MOTIVATION, (6) EMOTIONAL BEHAVIOR, AND (7) SOCIAL BEHAVIOR. IN EACH OF THESE 7 AREAS, THE BASIC CONCEPTS INVOLVED ARE EXPLICATED, CURRENT EXPERIMENTAL WORK OR THEORIES ARE SURVEYED, AND SPECIFIC PROPOSALS FOR APPLYING EACH TYPE OF ASSESSMENT TO PRESCHOOL CHILDREN ARE GIVEN. (DR)