" AcadBmy af Management /ournal 1993, Vol. 36, No. 5, 996-1025. ORGANIZATIONAL DEMOGRAPHY IN JAPANESE FIRMS: GROUP HETEROGENEITY, INDIVIDUAL DISSIMILARITY, AND TOP MANAGEMENT TEAM TURNOVER MARGARETHE F. WIERSEMA University of California, Irvine ALLAN BIRD New York University This study demonstrates how demography theory can be extended to non-U.S. settings by developing a comprehensive model of factors tbat vary across nations and that may moderate tbe link between demo- graphic characteristics and organizational outcomes. We propose tbat constraints on variation as well as socioculhiral and organizational processes moderate tbe attention people pay to individual differences, thereby influencing demographic effects. In examining the effects of tbe composition of top management teams in Japanese firms, we found that heterogeneity on age, team tenure, and tbe prestige of tbe university attended were significant correlates of team turnover. Moreover, tbese findings were substantially stronger than those of comparahle studies in the United Stales, suggesting tbat factors associated witb changes in etbnological context mediate demographic effects. Demography theory has generated considerable interest because of its theoretical importance in the study of organizations (Stinchcomhe, McDill, & Walker, 1968). Organizational demography reflects similarity and dissim- ilarity among individuals, making it a meaningful perspective for under- standing processes affected hy group dynamics, such as the level and extent of within-group communication, as well as outcomes of group dynamics, including such phenomena as the level of consensus within a group, inno- vation, and turnover. Demography theory's focus on how compositional characteristics influence interpersonal dynamics within a group of individ- uals makes it particularly relevant to understanding outcomes involving the top management teams of organizations (Pfeffer, 1983). Recent research has highlighted the importance of top management team demographic compo- sition on a variety of phenomena, including executive turnover (Jackson, Brett, Sessa, Cooper, Julin, & Peyronnin, 1991; Wagner, Pfeffer, & O'Reilly, We would like to thank this journal's reviewers for their helpful comments on earlier drafts of this article. We gratefully acknowledge the research support provided by the University of California, Irvine Academic Senate Committee on Research and the Fulhright Foundation. 996