Using data collected from a sample of 50 academic departments over the years 1977-88, the authors test several hypotheses about the effects of departmental gender composition on faculty turnover. They find that as the proportion of women in a department grew, turnover among women also increased, confirming the prediction that increases in the relative size of a minority will result in increased intergroup competition and conflict. The evidence also suggests, however, that when the proportion of female faculty reached a threshold of about 35-40%, turnover among women began to decline. The proportion of women had a negligible or negative impact on turnover among male faculty. The authors discuss the implications of this research for the implementation of affirmative action policies.