This paper addresses two issues arising from the changing pattern of doctorate production in American universities in last forty years. First, there has been a large increase in the number of doctorates awarded to foreign students. This leads to the concern that foreign doctorates have crowded out native doctorates especially certain groups of native doctorates such as native male and minorities. Second, graduate programs are increasingly becoming “feminine,” and some academic fields have already witnessed a ratcheting process toward female. This gives rise to concern about gender segregation among academic fields. Using data on the number of doctorates awarded in all academic fields from 1966 to 2002, this study examines the crowding-out effect and the tipping effect systematically. In science and engineering fields, there is no evidence of crowding-out between foreign doctorates and native doctorates. Outside of science and engineering, there is a strong negative correlation between the number of foreign doctorates and native male doctorates; however, non-science education accounts for almost all the negative association, suggesting the inappropriateness of aggregating fields in examining the crowding-out effect. Male students, especially native male students, exhibit strong “women-avoiding” behaviors in selecting academic fields of doctoral study, suggesting that native male students opt out of, instead of being crowded out of fields with a high proportion of female doctorates. As the gender composition of college graduates has started to stabilize in recent years, it is unlikely that those fields that already have a high proportion of female doctorates will be tipping toward all female.