MEXICAN-AMERICAN STUDENTS FROM 8 GRADE LEVELS WITHIN THE SAN YSIDRO, CALIFORNIA, ELEMENTARY SCHOOL DISTRICT WERE TESTED IN JUNE, 1967, AS PART OF AN EVALUATION OF THE RURAL MEXICAN-AMERICAN STUDENT POPULATION IN CALIFORNIA. ANALYSIS OF TEST RESULTS REVEALED THAT MEXICAN-AMERICAN STUDENTS FELL PROGRESSIVELY BEHIND IN PERCEPTUAL MOTOR DEVELOPMENT--A DEFICIT ATTRIBUTED TO BOTH HOME AND SCHOOL ENVIRONMENTS. LOW SELF-CONCEPT SCORES AND ABOVE-NORMAL SOCIAL MATURITY SCORES MAY HAVE REFLECTED THE DEMANDS OF 2 CULTURES ON THE MEXICAN-AMERICAN STUDENT. ACADEMIC ACHIEVEMENT PROGRESSIVELY DECLINED, POSSIBLY AS A RESULT OF THE DE-EMPHASIZING OF INDIVIDUALIZED INSTRUCTION AND THE ABSTRACTION DEMANDS MADE ON MEXICAN-AMERICAN STUDENTS BY MATERIALS GEARED TO MIDDLE-CLASS NORMS. TABLES SHOW WHICH TESTS WERE GIVEN TO WHICH GRADE LEVELS, AGE-GRADE RELATIONSHIPS, AND RESULTS BY INDIVIDUAL TEST. RELATED DOCUMENTS ARE RC002539 AND RC001775. (JEH)