Some authors have explained the dearth of women leaders as an "opt-out revolution"—that women today are making a choice not to aspire to leadership positions. The authors of this article present a model that tests managers’ biased evaluations of women as less career motivated as an explanation for why women have lower managerial aspirations than men. Specifically, they hypothesize that day-to-day managerial decisions involving allocating challenging work, training and development, and career encouragement mean women accrue less organizational development, and this is one explanation for their lower managerial aspirations. The authors’ model is based on social role theory and is examined in a sample of 112 supervisor–subordinate dyads at a U.S. Fortune 500 firm.