THE RELATIONSHIP OF EDUCABLE MENTAL RETARDATES IN REGULAR CLASSES AND SPECIAL CLASSES WITH RESPECT TO VOCABULARY WAS STUDIED. THERE WERE 49 SUBJECTS TAKEN FROM REGULAR CLASSES AND 45 FROM SPECIAL CLASSES. THE PRIMARY AND ELEMENTARY FORMS OF THE WORD MEANING SECTION OF THE STANFORD ACHIEVEMENT TESTS WERE ADMINISTERED TO EACH SUBJECT BY FOUR PERSONS ENGAGED IN THIS PROJECT. TESTS WERE READ TO EACH SUBJECT SEPARATELY. BOTH FORMS OF THE STANFORD ACHIEVEMENT TESTS WERE GIVEN TO ASCERTAIN THE RECOGNITION VOCABULARY OF SUBJECTS USED IN THIS STUDY. WITH THESE TESTS, EACH SUBJECT'S VOCABULARY WAS TESTED WITH RESPECT TO THE WORDS THAT HE COULD CORRECTLY RECOGNIZE WHEN HE HEARD THEM. CORRELATION COEFFICIENTS WERE COMPUTED TO DETERMINE THE RELATIONSHIP BETWEEN MENTAL AGE AND RECOGNITION VOCABULARY AND FUNCTIONAL VOCABULARY FOR EACH GROUP, AND BETWEEN SOCIAL AGE AND RECOGNITION VOCABULARY AND FUNCTIONAL VOCABULARY FOR EACH GROUP. ADDITIONAL EXPERIMENTAL STUDIES ARE NEEDED TO DETERMINE THE RELATIONSHIP BETWEEN EDUCABLE MENTAL RETARDATES IN REGULAR AND SPECIAL CLASSES WITH RESPECT TO SOCIAL DEVELOPMENT AND SPEAKING VOCABULARY. ALSO A COMPARATIVE STUDY OF VERBAL OUTPUT AND SOCIAL DEVELOPMENT SHOULD BE MADE OF FAMILIAL EDUCABLE MENTAL RETARDATES AND NONFAMILIAL EDUCABLE MENTAL RETARDATES. (JL)