Based on intensive research in interdisciplinarity in the natural sciences, Laurel Smith-Doerr and Jennifer Croissant engage the question of gender differences in the practice of interdisciplinary collaboration. This is a topic that receives relatively little attention, and the authors identify mixed signals for women scientists—a catch-22 in which women are, often simultaneously, expected to work in interdisciplinary ways (partly due to gender stereotypes), while also advised that doing so is too risky for career development.