Although in the early years of the Journal leadership research was rare and focused primarily on traits differentiating leaders from nonleaders, subsequent to World War II the research area developed in 3 major waves of conceptual, empirical, and methodological advances: (a) behavioral and attitude research; (b) behavioral, social-cognitive, and contingency research; and (c) transformational, social exchange, team, and gender-related research. Our review of this work shows dramatic increases in sophistication from early research focusing on personnel issues associated with World War I to contemporary multilevel models and meta-analyses on teams, shared leadership, leader-member exchange, gender, ethical, abusive, charismatic, and transformational leadership. Yet, many of the themes that characterize contemporary leadership research were also present in earlier research. (PsycINFO Database Record
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