Colorado Voters to Decide on Biological Sex Requirements for School Sports in Proposition 134

The conservative issue committee Protect Kids Colorado argues that Proposition 134 is a straightforward measure to protect fairness in girls' sports by keeping biological males off female teams. However, the actual text of the November ballot initiative mandates that all K-12 and collegiate athletes compete based on their "biological reproductive system," a requirement that opponents note would subject any student to anatomical verification just to participate in school athletics.[1][4]

Certified for the November 3, 2026, ballot, Proposition 134 asks Colorado voters whether to add a new article to the state's Revised Statutes. The measure requires all public schools, universities, and athletic associations to designate intramural and competitive teams as male, female, or coeducational, strictly overriding current state law that allows students to participate on teams aligning with their gender identity.[1][2]

Under the proposed framework, teams designated for females would be legally closed to male students. The initiative defines males as individuals whose reproductive systems are organized around the production of sperm, and females as those whose systems produce ova. Females would be permitted to play on male-designated teams only if no corresponding female team exists for a given sport.[4]

The campaign behind the measure, Protect Kids Colorado, submitted nearly 170,000 signatures earlier this year to qualify the initiative—formerly known as Initiative 109—for the ballot. The group's stated position is that biological males possess physical advantages that compromise the dignity, safety, and opportunity of female athletes in the state.[3][4]

"Bigger, stronger biological males are invading girls' sports in Colorado, taking away our girls' dignity, safety, and opportunity," the Protect Kids Colorado campaign stated in its official ballot arguments. "Our ballot measure ensures girls' sports are protected... Because girls' sports in Colorado should be for girls."[4]

In response, a coalition of parents, healthcare providers, and LGBTQ+ advocacy organizations formed the "Families Not Politics" campaign to defeat the measure. The opposition argues the proposition is vaguely written and forces government intrusion into personal health decisions, potentially subjecting young children to unnecessary medical scrutiny.[4]

Nadine Bridges, executive director of One Colorado, which leads the opposition campaign, criticized the measure's enforcement mechanisms. Bridges argued that the proposition leaves critical questions unanswered regarding who decides which students get questioned or inspected, warning that such vague laws open the door to harassment of any student who does not fit traditional gender expectations.[4]

The financial battle over the initiative has already surpassed $1.4 million. As of early September 2026, Families Not Politics had raised approximately $1.31 million to fight the measure, significantly outpacing the $152,000 raised by Protect Kids Colorado.[4]

Proposition 134 is one of 14 statewide measures facing Colorado voters this November, sharing the ballot with questions on tax restructuring, criminal justice, and a separate measure—Proposition 135—that seeks to prohibit gender-transition surgeries for minors.[1][2]

Colorado is one of several states bringing transgender sports participation directly to voters in 2026. The outcome in a traditionally Democratic-leaning state will serve as a major test of whether direct democracy campaigns can successfully implement restrictions in states where legislative efforts to ban transgender athletes have previously failed.[1][4]