The Gay Games’s policy on transgender athletes provides a model that could be adopted by many ‘mainstream’ sporting events. The Gay Games, a major international multi-sport event, is underway in Hong Kong and Guadalajara, Mexico. As seen with the FIFA Women’s World Cup and the Summer Paralympics, mega sporting events play an important role in celebrating human diversity. But the Gay Games has a particularly compelling history in this respect: Founded in 1982, at the beginning of the HIV/AIDS epidemic and the ensuing moral panic, the Gay Games has allowed LGBTQIA+ athletes to participate without stigma and fully be themselves. This year, the Gay Games continue to provide timely, valuable lessons in inclusion. In particular, its gender policy — which allows athletes to participate in the gender division with which they self-identify — provides a model that could be adopted by many ‘mainstream’ sporting events. The 2023 Games follow many months of global headlines focusing on debates around which gender divisions transgender athletes should be allowed (or not allowed) to compete in. In Australia, transgender children’s participation in sport was heavily debated during the 2022 Federal Election. The issue has spilled over into school sports, particularly in the US, where 20 states have imposed bans on trans athletes within schools or universities. A cascade of international sporting associations have also tightened rules concerning transgender athletes in recent years. In 2020, World Rugby banned transgender athletes from competition, followed by international cycling (UCI), swimming (FINA) and World Athletics banning trans women from women’s events. In the US, the issue has become such a political hot topic that CNN has described restricting trans rights as a new potential “litmus test for Republican candidates”. At the elite level, most major sporting events have historically operated on a two-sex system, which adopts a binary view of sex and determines sex as either male or female by external anatomical criteria deemed at birth. The Olympic Gamess — the largest sporting event in the world — has a complex history of sex-verification tests. Over the decades, the International Olympic Committee has used and rejected various verification techniques, including visual inspection (1948), manual inspection (1966), chromatin testing (1967) and testosterone testing (2006). These techniques were not just humiliating at times, but were also deemed scientifically unreliable for determining whether a body was ‘female’ or not. The testosterone testing regime has also been revised three times since 2011, after experts disagreed on the scientific reliability of various tests. This two-sex system facilitates sexism generally and transphobia specifically, researchers Richard Pringle and Erik Denison have argued. Despite being pervasive in sport, this binary division does not match what science knows about sexual anatomy, the researchers have explained. That is, science has been unable to determine with any consistency the factors or substances that constitute a female or male body. As early as the mid-19th century, French anatomist Isidore Geoffroy Saint-Hilare asserted that human sexual anatomy consisted of five category types. And in 2015, science journalist Claire Ainsworth, in an article in Nature on the difficulties of sex verification and the comprehension of sex as a spectrum, wrote, “[I]f you want to know whether someone is male or female, it may be best just to ask.” So too is the same advice for gender. A recent research paper in Integrative and Comparative Biology explained that “sex and gender are both complex and multifaceted”, adding: “There is a remarkable level of diversity within and between sexes and sex traits of individuals.” Internationally, sports such as surfing have recently created new policies for gender categorisation, reflecting the tensions around competition, inclusion, fairness and encouraging greater participation. The International Surfing Association Transgender Policy adopted this year by World Surfing League, for example, requires testosterone testing, but is less aggressive in those requirements compared with other international-level sports such as athletics. In general, grassroots or community surfing seems more willing to deal with these issues in a trans-inclusive way than elite, international-level events, as forthcoming research by lisahunter explores. The Gay Games — which focus on participation and inclusion, rather than the overt desire to determine athletic supremacy — has taken a different approach to the Olympics and other major ‘mainstream’ events.