As with general leadership studies, there has been increasing interest in what actions project leaders take to complete projects successfully. However, this area has received little attention as well.
One of the earlier comprehensive works on what project leaders do is the work of Wendy Briner, Michael Geddes, and Colin Hastings, which appeared in their book, Project Leadership . They list several actions of a good leader to include building credibility, creating a supportive culture, providing purpose and direction, and seeking feedback. 
Dr. Edward Hoffman and Dr. Alexander Laufer conducted a study based on stories told to them by project leaders. They capture "critical incidents" of successful project leadership. According to the authors, this knowledge is often tacit, which makes it difficult to quantify. Stories are one way to make such knowledge explicit.
They identify twenty-four patterns of behavior, summarized in four rules: adopt a will to win, create a results-oriented focus, foster sensitivity to context, and collaborate through trust.
Adopting a will to win is basically being a "man on a mission" who is willing to take calculated risks and "weather the storm ." Creating a result-oriented focus is knowing what to achieve, identifying the means to get it, and moving with deliberate speed. Fostering sensitivity to context is being adaptable on both formal and informal approaches as well as being the project's advocate. Collaborating through trust is developing and sustaining commitment from all stakeholders. 
In an article for PM Network , Owen Gadeken described his research on project managers in the defense industry. He suggested that project managers now and in the future perform four roles: Strategy Setter, Consensus Builder, Systems Integrator, and Change Agent.
A Strategy Setter establishes goals and demonstrates commitment to achieve them. A Consensus Builder generates a sense of community through consensual decision making. A Systems Integrator brings together all the elements of a project and forms a cohesive whole. A Change Agent recognizes the need for change and embraces new ways of doing business. 
 Wendy Briner, Michael Geddes, and Colin Hastings, Project Leadership , Gower, Aldershot, Hampshire, U.K., 1990, pp. 18 “30.
 Edward J. Hoffman and Alexander Laufer, Emerging research into factors of project success and failure, PMI Research Conference 2002, July 15, Seattle, WA, pp. 1 “30.
 Owen C. Gadeken, Third wave project leadership, PM Network , pp. 43 “46, February 1999.