The U.S. Naval Postgraduate School Test, Form ZNP, was the outcome of a three-year research program carried out by Educational Testing Service for the Naval Postgraduate School. During this three-year period, three experimental batteries were developed and tried out at the School, with subsequent validation against criteria of academic success. The operational test consists of Mathematics Aptitude, Advanced Mathematics, Physical Science and Engineering, Interpretation of Scientific Data, and Experimental Science sections. This report presents further information on the effectiveness of these sections for predicting success at the School, based on further validation of tests given in 1949 and 1950 which correspond to the sections of Form ZNP. Two main outcomes of the study are (1) for the most part, results corroborate earlier findings as to test validity; and (2) the effectiveness of the tests given "in the fleet" in the fall of 1949 was considerably lower than when the same tests were given at the School.