DEFINING MUSICALITY AS THE ABILITY TO GRASP A MUSICAL IDEA IN ITS TOTALITY, THIS RESEARCH INVESTIGATED THE RELATIVE EFFECTIVENESS OF MUSICAL PERFORMANCE (BOTH ORCHESTRAL AND CHORAL), GUIDED LISTENING, MUSIC READING, AND MUSICAL COMPOSITION AS MEANS OF DEVELOPING SUCH MUSICALITY. THE INSTRUMENT OF EVALUATION WAS A TEST OF AESTHETIC JUDGMENTS IN MUSIC DERIVED FROM THE WING, HEVNER, GORDON, AND KYME TESTS OF MUSICALITY WHICH ARE EMPIRICALLY VALIDATED WITH TEACHER RATINGS OF PUPILS. NINE JUNIOR HIGH SCHOOLS COMPRISED THE SAMPLE. THE 3,083 STUDENTS PARTICIPATING INCLUDED A ZERO CONTROL SAMPLE OF 671 STUDENTS WHO TOOK NO MUSIC CLASSES DURING THE TIME OF EXPERIMENT, AN EXPERIMENTAL SAMPLE OF 555 WHO WERE TAUGHT COMPOSITION, 645 ORCHESTRA STUDENTS, 737 CHORAL STUDENTS, 405 WHO PARTICIPATED IN GUIDED LISTENING, AND 70 STUDENTS CLASSED AS A MUSIC READING CONTROL. THE STATISTICAL TREATMENT OF THE DATA (PRE- AND POST-INSTRUCTION TEST SCORES) UTILIZED AN ANALYSIS OF COVARIANCE. THE EXPERIMENTAL SAMPLE SHOWED SIGNIFICANT GAINS COMPARED TO THE ZERO CONTROL (F VALUE=54.47), THE CHORAL SAMPLE (F=29.42), AND THE LISTENING CONTROL (F=11.78). THE GAINS OF THE ORCHESTRAL AND CHORIC READING SAMPLES WERE NOT SIGNIFICANTLY DIFFERENT FROM THOSE OF THE EXPERIMENTAL. ANALYSIS OF DATA, SCHOOL BY SCHOOL, REVEALED THAT MUSICAL COMPOSITION IS MOST EFFECTIVE AT HIGHER SOCIOECONOMIC LEVELS, THOUGH INSTRUMENTAL PERFORMANCE IS THE MOST UNIVERSAL EFFECTOR. THE GUIDED LISTENING PROGRAM WAS NOT PRODUCTIVE FOR SCHOOLS CLASSED AS CULTURALLY DEPRIVED. MUSIC READING WAS THE MOST EFFECTIVE LEARNING TOOL FOR THE LOWER SOCIOECONOMIC SCHOOLS. (HM)