The Maryland House of Delegates is considering HB 63, a bill that would ban transgender students from participating in certain school-based sports by adopting a narrow definition of sex. The National Women’s Law Center Action Fund submitted written testimony in opposition to HB 63, which outlined how exclusionary sports policies reinforce sexist stereotypes about the athletic abilities of women and girls and ultimately encourage gender policing of student activities, opening the door to inappropriate inquiries, further harassment of women and girls, and even sex testing. All athletes—regardless of gender—come in different shapes, sizes, and physical makeups; adopting categorical bans that bar transgender students’ participation does nothing to strengthen women’s and girls’ sports, but rather creates more hostile athletic environments for cisgender and transgender students alike.