The objective of this research is the development of personality measures to supplement the more scholastically oriented aptitude tests used in the selection of Naval Officers. The first year's work, recently completed, was concerned with a study of associates' and officers' ratings of U.S. Naval Academy midshipmen on "aptitude for service," or leadership potential. Intercorrelations were computed among aptitude for service ratings for three summer cruises and two academic periods, standings in academic courses, and scholastic aptitude test scores, using 633 members of the class of 1951. Results indicated that the aptitude ratings were quite clearly differentiated from academic standing, and from verbal, mathematical, and spatial ability. Considerable stability was found in the ratings from one marking period to another, except for cruise ratings. A more detailed analysis of the ratings given and received by about 200 midshipmen from the larger group indicated that the composite ratings by fellow midshipmen were highly reliable. There was some evidence indicating a slight tendency for raters who agreed with composite opinion in judging their associates, to stand high themselves in aptitude for service. Little or no relationship was found between aptitude for service and a number of biographical factors such as age, previous military service, amount and type of previous education, etc. On the basis of the first year's work, it was felt that the aptitude ratings represented a suitable first criterion, and hence it was considered advisable and worth-while to proceed with the development and initial validation of personality measures to predict this criterion. This constitutes the objective of the second phase of the investigation which was recently initiated.