Between 1972 and 1978 U.S. high schools rapidly increased their female athletic participation rates--to approximately the same level as their male athletic participation rates--in order to comply with Title IX, a policy change that provides a unique quasi-experiment in female athletic participation. This paper examines the causal implications of this expansion in female sports participation by using variation in the level of boys' athletic participation across states before Title IX to instrument for the change in girls' athletic participation. Analysis of differences in outcomes across states in changes between pre- and post-cohorts reveals that a 10-percentage point rise in state-level female sports participation generates a 1 percentage point increase in female college attendance and a 1 to 2 percentage point rise in female labor force participation. Furthermore, greater opportunities to play sports leads to greater female participation in previously male-dominated occupations, particularly in high-skill occupations.