Women have made significant strides toward equal representation within the U.S. Congress, but their seat share has mostly increased within the Democratic—but not Republican—Party. We argue that one driver of women’s underrepresentation among Republicans is the proliferation of safe seats. Because safe seats encourage ideological extremism in candidates and because women are stereotyped as more liberal than men, we expect women candidates to outperform men in safer Democratic seats but underperform men in safer Republican seats (relative to more competitive seats). Based on a new dataset linking all candidates for the U.S. House and their districts’ partisan composition since 2000, we show women both enter and win elections in safer Republican (Democratic) seats at relatively lower (higher) rates than men. Our results strikingly suggest that, even conditional on running, a female Republican candidate has an overall better chance of winning in a competitive seat than in a safe Republican seat.