We study the role of self-promotion and career advice in sustaining gender differences in labor market outcomes. We conduct an online experiment in which “advisers” advise “workers” to choose between a more ambitious and a less ambitious task based on the worker’s subjective self-assessment. We find that women have lower self-assessments and receive less ambitious career advice as a result. We also show that these gender differences are similar for both quantitative and qualitative self-assessments, and that the gender difference in advice received can be mitigated by informing advisers of the workers’ true performance or of the gender gap in self-promotion.