USING A CONCEPTUAL MODEL DRAWN FROM SYSTEMS-ORIENTED THINKING AND RESEARCH IN DEVELOPMENTAL PSYCHOLOGY, A LIMITED NUMBER OF SCHOOL UNDERACHIEVEMENT PROBLEMS WERE ANALYZED. SCHOOL UNDERACHIEVERS ARE VIEWED AS BIOLOGICAL SYSTEMS TRANSACTING WITH A VARIETY OF SOCIAL SYSTEMS. THEREFORE, THE FOCUS IS ON FINDING PROBLEM-PRODUCING ELEMENTS IN THE TOTAL SYSTEM. SINCE INTERACTION WITH A SOCIAL SYSTEM IS BEST UNDERSTOOD IN ITS DEVELOPMENTAL CONTEXT, THE UNDERACHIEVER'S BEHAVIOR IS STUDIED IN TWO WAYS--(1) AS IT REFLECTS HIS DEVELOPMENTAL LEVELS, AND (2) AS IT REFLECTS DEVELOPMENTAL LEVELS OF INTERACTING ENVIRONMENTAL SYSTEMS. CASES REPRESENTING POSSIBLE TYPES OF UNDERACHIEVEMENT ARE PRESENTED. THESE CASES DEMONSTRATE A SYSTEMS AND DEVELOPMENTAL APPROACH IN THE SOLUTION. RECOMMENDATIONS ARE BASED ON AN ANALYSIS OF THE SYSTEM IN WHICH CULTURALLY DISADVANTAGED CHILDREN LIVE, AND THE DEVELOPMENTAL DEFICITS PRODUCED. CHANGES ARE NEEDED WITHIN THE SCHOOL, FOR IT IS THE SYSTEM DESIGNATED TO COPE WITH THESE PROBLEMS. (PH)