IN ORDER TO INVESTIGATE THE EFFECTIVENESS OF MONTESSORI PRESCHOOL EDUCATION AS COMPARED WITH NON-MONTESSORI PRESCHOOL EDUCATION, PHASE I OF THIS STUDY MATCHED 2 GROUPS, EACH OF 21 PRESCHOOL CHILDREN, ON INTELLIGENCE QUOTIENT AND CERTAIN SOCIO-ECONOMIC FACTORS. ONE GROUP ATTENDED A MONTESSORI PRESCHOOL AND THE OTHER A NON-MONTESSORI PRESCHOOL. THE CHILDREN WERE ADMINISTERED TESTS NEAR THE BEGINNING AND END OF THE PRESCHOOL YEAR TO DETERMINE ANY DIFFERENCES IN ACHIEVEMENT DUE TO THE PRESCHOOL TRAINING. IN PHASE II A TRAINED RESARCHER INTERVIEWED THE PRIMARY GRADE TEACHERS WHO BY THEN HAD SOME OF THE PRESCHOOL CHILDREN OF PHASE I IN THEIR CLASSROOMS. RATINGS OF THESE TEACHERS PROVIDED INFORMATION ON THE PERSONALITY AND ABILITY OF 3 GROUPS OF CHILDREN, (1) FORMER MONTESSORI PRESCHOOL CHILDREN, (2) FORMER NON-MONTESSORI PRESCHOOL CHILDREN, AND (3) NON-PRESCHOOL CHILDREN. THE CHILDREN WERE RATED ON 8 MAJOR TRAITS WHICH CONTAINED 27 STIMULUS VARIABLES. PHASE I DATA INDICATED THAT MONTESSORI PRESCHOOL CHILDREN GAINED SIGNIFICANTLY MORE IN VERBAL ABILITY THAN NON-MONTESSORI PRESCHOOL CHILDREN. PHASE II DATA INDICATED THAT MONTESSORI CHILDREN WERE SUPERIOR TO THE CHILDREN OF THE OTHER 2 GROUPS IN READING READINESS, INTEREST IN LEARNING, INDEPENDENCE, INTERPERSONAL RELATIONS, LEADERSHIP, AND LEARNING ABILITY. NO DIFFERENCES WERE FOUND IN CREATIVITY OR ABILITY TO ADJUST TO THE TRADITIONAL-TYPE SCHOOL. (WD)