The National Association of Intercollegiate Athletics announced a policy Monday that all but bans transgender athletes from competing in women’s sports at its 241 mostly small colleges across the country.

The NAIA Council of Presidents approved the policy in a 20-0 vote at its annual convention in Kansas City, Missouri. The NAIA, which oversees some 83,000 athletes competing in more than 25 sports, is believed to be the first college sports organization to take such a step.

According to the transgender participation policy, all athletes may participate in NAIA-sponsored male sports but only athletes whose biological sex assigned at birth is female and have not begun hormone therapy will be allowed participate in women’s sports.

A student who has begun hormone therapy may participate in activities such as workouts, practices and team activities, but not in interscholastic competition.