This article presents a synthesis of research on the relative effectiveness of women and men who occupy leadership and managerial roles. Aggregated over the organizational and laboratory experimental studies in the sample, male and female leaders were equally effective. However, consistent with the assumption that the congruence of leadership roles with leaders' gender enhances effectiveness, men were more effective than women in roles that were defined in more masculine terms, and women were more effective than men in roles that were defined in less masculine terms. Also, men were more effective than women to the extent that leader and subordinate roles were male-dominated numerically. These and other findings are discussed from the perspective of social-role theory of sex differences in social behavior as well as from alternative perspectives.