THIS PROJECT WAS CONDUCTED TO INVESTIGATE THE EFFECT UPON DISADVANTAGED CHILDREN OF A HEAD START PROGRAM AND THE AFTER-EFFECT OF THAT PROGRAM ON THE SUBJECTS' SUBSEQUENT PERFORMANCE IN KINDERGARTEN AND FIRST GRADE. MEASURES OF APTITUDE AND ACHIEVEMENT WERE TAKEN DURING THE FIRST TWO WEEKS AND LAST TWO WEEKS OF THE EIGHT WEEK HEAD START PROGRAM, DURING THE THIRD MONTH OF THE SUBJECTS' FIRST YEAR OF FORMAL SCHOOL, AT THE COMPLETION OF THAT FIRST YEAR, AND DURING THE FIRST SIX MONTHS OF THEIR SECOND YEAR OF SCHOOL. RESULTS OF TESTING DURING THE HEAD START PROGRAM SHOWED SUBSTANTIAL GAIN IN ALL PERFORMANCE AREAS BETWEEN THE TWO TESTING PERIODS. NO CONTROL GROUP WAS USED. THEREFORE, NO EXPERIMENTALLY BASED CONCLUSION COULD BE MADE AS TO WHETHER THE GAIN WAS DUE TO THE HEAD START EXPERIENCE OR TO A SIMPLE PASSAGE OF TIME AND RESULTING GENERAL DEVELOPMENT. MEASURES OF PERFORMANCE AFTER THE SUBJECTS ENTERED SCHOOL SHOWED NO SIGNIFICANT GAINS BY HEAD START PUPILS OVER NON-HEAD START PUPILS. THE ONLY REAL DISTINCTION WAS IN SCHOOL ATTENDANCE, IN WHICH HEAD START PUPILS DID BETTER. THE FACT THAT THE EXPERIMENTAL SUBJECTS SHOWED HIGH GAINS DURING THE HEAD START PROGRAM BUT FAILED TO EVIDENCE SUCH GAINS IN THE FORMAL SCHOOL SITUATION WAS EXPLAINED IN PART AS DUE TO THE FACT THAT THE CHILDREN WERE EMOTIONALLY UNREADY AT THE BEGINNING OF THE HEAD START PROGRAM TO BE TESTED BY RELATIVE STRANGERS IN UNFAMILIAR SURROUNDINGS. IT IS HYPOTHESIZED, THEREFORE, THAT THE CHILDREN SCORED UNCHARACTERISTICALLY LOW. (WD)