The NCAA has decided it will not send tournaments to any state that prohibits boys from playing on girls’ athletic teams, joining a growing list of academic and corporate groups that are quick to elevate fringe social opinions over science and rationale. No one is arguing that transgender athletes should not be able to compete—but allowing them to do so while competing against the opposite biological sex threatens to undermine decades of progress made for female athletes across the nation. The science is clear—there are fundamental biological differences between men and women, and those differences are made evident time and again in athletic competitions. Collegiate female athletes deserve better from higher ed institutions like the NCAA which used to stand for equal treatment and fair competition.