The aim of this study was to construct and validate a biographical inventory to measure personality traits that are predictive of leadership. The experimental inventory, consisting of tentative scales for Dominance, Emotional Stability, Need for Achievement, Self-Confidence, and Sociability, was administered to 642 incoming midshipmen at the Naval Academy. The tentative scales were item analyzed, and the validity of the final scales was appraised against subsequent peer ratings of the traits and of leadership, as well as against first-semester grades that may reflect leadership (Military Performance and Professional Military Quality Point Rating). The Sociability, Dominance, and Need for Achievement scales demonstrated convergent and discriminant validity and correlated with the leadership criteria; the Emotional Stability and Self-Confidence scales showed no signs of validity. Although the level of validity was often modest, the Sociability scale correlated appreciably (0.28) with the peer rating of leadership, suggesting that this measure may have practical value in assessing leadership potential. (Contains 1 figure, 15 tables, and 16 references.) (Author/SLD)