THIS SHORT-TERM EVALUATION OF THE MORE EFFECTIVE SCHOOLS (MES) PROGRAM IN 21 NEW YORK CITY PUBLIC ELEMENTARY SCHOOLS ASSESSED THE MES INSTRUCTIONAL PROGRAM AND ITS IMPACT ON THE STUDENTS. DATA WERE GATHERED FROM (1) OBSERVATIONAL VISITS TO CLASSROOMS BY TWO-MEMBER TEAMS OF EDUCATORS AND SOCIAL SCIENTISTS, (2) STRUCTURED INTERVIEWS WITH ADMINISTRATIVE AND TEACHING STAFF, (3) INVENTORIES ADMINISTERED TO THE CHILDREN TO ASSESS THEIR PERCEPTIONS OF SELF AND SCHOOL, AND (4) STUDENT'S SCORES ON THE METROPOLITAN ACHIEVEMENT TEST IN ARITHMETIC AND READING. DATA WERE ALSO COLLECTED ABOUT TEACHERS' ATTITUDES AND BEHAVIOR, CLASS SIZE, GROUPING PRACTICES, SCHOOL CLIMATE, ETHNIC COMPOSITION, ATTENDANCE, AND COSTS. THESE DATA WERE COMPARED WITH EVALUATIVE DATA FROM EIGHT CONTROL SCHOOLS AND FROM THE 1966-67 EVALUATION OF THE FREE CHOICE OPEN ENROLLMENT PROGRAM. IT WAS FOUND THAT THE EFFECTIVENESS OF THE PROGRAM VARIED CONSIDERABLY WITH EACH SCHOOL, BUT THE GENERAL MES ATMOSPHERE AND STAFF, PARENT, AND COMMUNITY ATTITUDES TOWARD THE PROGRAM WERE ALL ENTHUSIASTIC AND OPTIMISTIC. HOWEVER THE PROGRAM HAD HAD NO SIGNIFICANT EFFECT ON STUDENT PERFORMANCE AND THE GAINS PER ACADEMIC YEAR WHICH HAD BEEN NOTED IN PREVIOUS EVALUATIONS WERE NOT BEING MAINTAINED. CHILDREN WHO HAD BEEN IN THE MES PROGRAM FOR THREE YEARS WERE EVEN FURTHER BEHIND NORMAL STANDARDS THAN WHEN THEY HAD BEGUN. THUS, ALTHOUGH ADMINISTRATIVE RESTRUCTURING (SMALLER CLASSES, SPECIAL SERVICES, ETC.) CREATED A GENERAL OPTIMISM, THE ABSENCE OF ANY SUCH RESTRUCTURING IN CURRICULUM AND IN BASIC TEACHING METHODS RESTRICTED PUPIL ACHIEVEMENT. (LB)