The present research examined whether gender-science stereotypes were associated with science identification and, in turn, science career aspirations among women and men undergraduate science majors. More than 1,700 students enrolled in introductory science courses completed measures of gender-science stereotypes (implicit associations and endorsement of male superiority in science), science identification, and science career aspirations. Results were consistent with theoretically based predictions. Among women, stronger gender-science stereotypes were associated with weaker science identification and, in turn, weaker science career aspirations. By contrast, among men stronger gender-science stereotypes were associated with stronger science identification and, in turn, stronger science career aspirations, particularly among men who were highly gender identified. These two sets of modest but significant findings can accumulate over large populations and across critical time points within a leaky pipeline to meaningfully contribute to gender disparities in STEM domains.