This article follows the call for more empirical research on leadership in different organizational contexts. Organizations react to environmental dynamism and uncertainty by using temporary forms or organizing such as projects. This organizational context factor raises questions about the nature of effective leadership in temporary settings. Transactional leadership has been found to be particularly effective in settings without a shared history of leaders and followers. In turn, prior research indicates that transformational leadership succeeds in times of uncertainty, which is essential to temporary organizations. We extend the existing transactional and transformational leadership approaches by examining leadership in the context of the temporary organization. We empirically test for effects of transactional and transformational leadership in projects and find that both leadership behaviors positively influence the followers’ commitment. However, transformational leadership is more effective than transactional leadership. The effects of both leadership behaviors are amplified by increasing complexity of the project.