a leadership theory stating that leaders will be effective insofar as they make it clear to followers how they can achieve goals and obtain rewards. By doing so, leaders enhance their followers’ expectancy that hard work will lead to task success and that task success will lead to valued rewards. The four basic leadership styles proposed in this theory are instrumental (directive), supportive, participative, and achievement-oriented leadership. Each of these styles can be effective or ineffective, depending on the nature of the work environment and the characteristics of subordinates. See also valence–instrumentality–expectancy theory.