This research is aimed at the development of personality measures to supplement the more scholastically oriented aptitude tests used in the selection of Naval Officers. The investigation is being carried out at the U.S. Naval Academy, with midshipmen being used as subjects. Considerable stress is being placed, particularly in the early states of the investigation, upon the establishing of satisfactory criterion measures and upon an understanding of the main components which appear to enter into the criterion, as prerequisites for adequate test construction and validation. It is anticipated that a suitable criterion measure can probably be developed from within the structure of the system presently in use at the Academy for grading midshipmen in aptitude for the service. An analysis of these aptitude for service ratings in order to determine their underlying components and to evaluate their suitability as criterion measures constitutes the first major phase of this research. Efforts will then be made to develop or select personality tests which will be of value in predicting this criterion.