The inclusion of girls and women in sport at all levels depends on single sex categories for most sports from puberty onwards, because of the biological differences between the sexes. Most sport is, by definition, competitive; involving invasion games, teams, leagues, races, competitions and sometimes rankings, from foundation to excellence. Girls and women are underrepresented, particularly in traditional sport, as recognised by the UK Sports Councils and most governing bodies of sport. This paper uses feminist philosophy: Lister on androcentric citizenship, (...) and Fraser on justice as balance, framing, recognition, representation and redistribution. It investigates the impact on the inclusion of girls and women, of eligibility policies adopting ‘self-identification of gender’ guidelines for the inclusion of transgender people in sport, at participation rather than elite levels. It explores fairness and equality as incorporated in law in the 2010 Equality Act in Britain, and contributes to ‘equality evidence’ available to the UK Sports Councils and GBS. These bodies are charged with developing fair and inclusive evidence-based eligibility criteria, in sports participation settings, for both girls and women, and transgender people. (shrink)