CHANGES IN ACADEMIC APTITUDE AND ACHIEVEMENT TEST SCORES OF PUPILS ATTENDING PUBLIC SCHOOLS IN DISADVANTAGED AREAS IN NEW YORK CITY WERE INVESTIGATED. AN ATTEMPT WAS MADE TO DETERMINE WHETHER VARYING DEGREES OF MOBILITY WERE ASSOCIATED WITH VARIATION IN CHANGES IN TEST SCORES. THE CUMULATIVE RECORD CARDS OF SIXTH-GRADE PUPILS WERE EXAMINED TO IDENTIFY PUPILS WHO MET SUCH CRITERIA AS HAVING ENTERED THE NEW YORK CITY SCHOOLS FOR THE FIRST TIME IN EITHER KINDERGARTEN OR FIRST GRADE AND HAVING UNINTERRUPTED ATTENDANCE IN THE REGULAR GRADES OF THE SCHOOLS. DATA COLLECTED CONCERNING THE NUMBER OF TIMES EACH PUPIL HAD BEEN ADMITTED TO A DIFFERENT SCHOOL IN THE CITY MADE IT POSSIBLE TO RECOGNIZE MOBILE PUPILS. PUPILS LIVING IN DISADVANTAGED AREAS DID NOT SHOW A DECLINE IN ACADEMIC APTITUDE OR READING TEST SCORES FROM THE THIRD TO THE SIXTH GRADE. DISADVANTAGED CHILDREN WHO HAD ATTENDED A SINGLE SCHOOL DURING THE SIX ELEMENTARY SCHOOL GRADES SHOWED IMPROVEMENT FROM THE THIRD TO THE SIXTH GRADES. DISADVANTAGED CHILDREN WHO ATTENDED MORE THAN ONE SCHOOL DURING THE SIX ELEMENTARY SCHOOL GRADES, HOWEVER, SHOWED A LACK OF IMPROVEMENT. ATTENDANCE IN FOUR OR MORE SCHOOLS DURING THE ELEMENTARY GRADES MARKEDLY AFFECTED PERFORMANCE. IN MANY CASES PUPILS SHOULD NOT HAVE BEEN TRANSFERRED TO PROVIDE BETTER ETHNIC BALANCE IN A SCHOOL. IT WOULD HAVE BEEN EDUCATIONALLY SOUNDER TO HAVE PROVIDED FUNDS FOR THE TRANSPORTATION OF MOBILE PUPILS SO THEY COULD HAVE REMAINED IN THE SCHOOL WHICH THEY ORIGINALLY ENTERED AND RECEIVED AN UNINTERRUPTED EDUCATIONAL EXPERIENCE RATHER THAN TO HAVE INCREASED THE DEGREE OF MOBILITY TO FOSTER OTHER EDUCATIONAL AND SOCIAL VALUES. THIS PAPER WAS PRESENTED TO THE CONFERENCE ON CURRICULUM AND TEACHING IN DEPRESSED URBAN AREAS (4TH, COLUMBIA UNIVERSITY, JUNE 21-JULY 2, 1965).