In this multi-source study we investigated the relationships between the Big Five personality traits and both charismatic and transactional leadership behavior, and whether dynamism (the degree that the work environment is deemed dynamic) moderates these relationships. We also tested whether dynamism moderates the relationship between leadership behavior and effectiveness. Personality was measured through self ratings using the NEO-PI-R. Subordinates rated their leaders' behavior, and peers and superiors provided ratings of effectiveness. Consistent with trait activation theory, results showed that perceived dynamic work environment moderated the relationships of four of the Big Five-Factors with both charismatic and transactional leadership. Also, charismatic leadership was positively related to perceived effectiveness, but only in dynamic contexts. Copyright © 2005 John Wiley & Sons, Ltd.