The relationship between measurements of personality and leadership is described in this paper. Following an introduction and a statement of the problem, the first part discusses the principles of measurement, beginning with the basic issues and assumptions and going on to examine various aspects of validity, reliability, instrument construction, and performance testing. The second part discusses personality and its definition, personality and leadership, traits and criticism of traits, adult personality development, identity, and personality testing. Issues in the study and measurement of leadership are described in the next part, with a focus on the uses of different instruments to measure leadership. Methods used by assessment centers are examined in the fourth part, with attention to the pros and cons of psychological testing and leaderless group discussions. The final part summarizes topics covered in each of the preceding sections. One conclusion is that the assessment center method is effective for direct observation of job-related skills, but that tests should be carefully selected, administered, and scored. The design of personnel policy must correspond with the use of appropriate measures. (Contains 86 references.) (LMI)