THE BEHAVIORAL NORMS OF LOWER CLASS DISADVANTAGED CHILDREN ARE DIFFERENT FROM CHILDREN IN MORE MIDDLE CLASS GROUPS. THE BEHAVIOR OF LOWER CLASS CHILDREN IS INFLUENCED NOT ONLY BY GENERAL SOCIAL CLASS AND CULTURAL BACKGROUND BUT ALSO BY SUCH SPECIFIC INTRACLASS VARIABLES AS FAMILY ENVIRONMENT. THE PRESENT ABSENCE IN THE LITERATURE AND IN PRACTICE OF ANY SYSTEMATIC FRAMEWORK OF DIFFERENTIATED CRITERIA FOR DIFFERENT POPULATION GROUPS MAY OBSCURE CERTAIN BEHAVIORAL SHIFTS OCCURRING AMONG LOWER CLASS CHILDREN WHEN THEY ARE OBSERVED IN A MIDDLE CLASS SETTING. TO DEMONSTRATE THE DIFFERENTIAL IMPACT OF CHILD REARING PRACTICES ON A CHILD'S BEHAVIOR AND COGNITIVE DEVELOPMENT, A STUDY OF A GROUP OF 3-YEAR-OLD CHILDREN WITH AMERICAN-BORN MIDDLE CLASS PARENTS AND A GROUP OF 3-YEAR-OLD PUERTO RICAN CHILDREN FROM WORKING CLASS HOMES WAS CONDUCTED. IT WAS FOUND THAT IN RESPONSE TO CERTAIN COGNITIVE TASK PERFORMANCE DEMANDS THE MIDDLE CLASS CHILDREN WERE LIKELY TO ENGAGE IN TASK PERFORMANCE BEHAVIOR AND WERE MORE VERBAL THAN WERE THE LOWER CLASS CHILDREN. DIFFERENCES IN THE KIND OF VERBALIZATIONS CHARACTERISTIC OF EACH GROUP WERE ALSO INDICATED. IT WAS ALSO FOUND THAT PUERTO RICAN FAMILIES DO NOT PARTICULARLY EMPHASIZE TASK MASTERY AND STRESS VERBALIZATION FOR SOCIAL REASONS ONLY. IF LOWER CLASS DISADVANTAGED CHILDREN ARE TO ACHIEVE IN TASK-ORIENTED MIDDLE CLASS SOCIETY, THEN KNOWLEDGE OF THESE BEHAVIORAL AND ATTITUDINAL DIFFERENCES MUST BE ACCOUNTED FOR AND PERHAPS EVEN ELIMINATED BY THE SCHOOLS. THIS PAPER WAS PREPARED FOR A.P.A. DIVISIONAL MEETING, NOVEMBER 17, 1967. (LB)