THE PURPOSE OF THE RESEARCH WAS TO OBSERVE THE CONSISTENCY OF INTRA-INDIVIDUAL VARIABILITY FROM ONE TASK TO ANOTHER, TO DETERMINE THE RELIABILITY OF OBSERVATIONS OF INTRA-INDIVIDUAL VARIABILITY, AND TO OBSERVE THE EXTENT TO WHICH THE ACCURACY OF PREDICTION VARIED WITH THE CONSISTENCY OF THE INDIVIDUAL'S BEHAVIOR. MALE ENGINEERING STUDENTS AT THE UNIVERSITY OF MINNESOTA WERE ADMINISTERED A BATTERY OF SIX BRIEF, INDEPENDENT TESTS ON EACH OF TWENTY DAYS. MOST OF THE OBSERVATIONS OF INTRA-INDIVIDUAL VARIABILITY WERE RELIABLE. VARIABILITY OVER TIME ON SOME TASKS IS RELATED TO VARIABILITY ON OTHER TASKS, BUT THESE RELATIONSHIPS ARE ONLY MODERATE AND THE HIGHEST CORRELATIONS BETWEEN ANY TWO OF THE VARIANCE INDICES WAS ONLY ABOUT .50. INTRA-INDIVIDUAL VARIABILITY IS NOT SPECIFIC TO EACH TASK BUT NEITHER IS THERE A BROADLY GENERALIZED CHARACTERISTIC OF SUCH VARIABILITY. A RELATIONSHIP WAS OBSERVED BETWEEN THE VARIABILITY OVER TIME OF A PERSON'S BEHAVIOR ON SIMPLE TASKS AND THE EFFECTIVENESS WITH WHICH HIS ACADEMIC PERFORMANCE CAN BE PREDICTED. SOME OF THE ANALYSES REVEALED ERRORS OF PREDICTION SIGNIFICANTLY SMALLER FOR THE LESS VARIABLE GROUP. CONSIDERED IN THE LIGHT OF RESULTS OF OTHER RESEARCH, THESE RESULTS SUGGEST THAT A COMPLEX BUT PRESUMEDLY USEFUL RELATIONSHIP EXITS BETWEEN THE CONSISTENCY OF AN INDIVIDUAL'S BEHAVIOR AND THE EXTENT TO WHICH HIS ACADEMIC BEHAVIOR IS PREDICTABLE. (AUTHOR)