The College Entrance Examination Board and later the Educational Testing Service, working in cooperation with and under the direction of the Bureau of Naval Personnel, has prepared, distributed, directed the administration of, scored, reported, and studied the results of the Navy College Aptitude Test administered in January 1947 in connection with the selection of NROTC students. The present study was undertaken to investigate the validity of the total score on this test as a predictor of first-year academic marks and of Naval Science marks in the 52 colleges having NROTC programs.