This article develops a supply-side mechanism about how cultural beliefs ab
out gender differentially influence the early career-relevant decisions of
men and women. Cultural beliefs about gender are argued to bias individuals
' perceptions of their competence at various career-relevant tasks, control
ling for actual ability. To the extent that individuals then act on gender-
differentiated perceptions when making career decisions, cultural beliefs a
bout gender channel men and women in substantially different career directi
ons. The hypotheses are evaluated by considering how gendered beliefs about
mathematics impact individuals' assessments of their own mathematical comp
etence, which, in turn, leads to gender differences in decisions to persist
on a path toward a career in science, math, or engineering.