HMC (The Headmasters' and Headmistresses' Conference) is a professional association of the Heads of the world's leading independent schools. It exists to serve and support its members, to represent their views and to exemplify excellence in education. HMC's membership includes the Heads of boarding and day schools, co-educational schools, single-sex schools, and 'diamond schools' where both single-sex and co-educational teaching takes place. The majority of HMC members' schools are based in the UK and Ireland, and the association has a growing number of International members. There are also a number of Affiliate members (the Heads of schools in school foundations led by an overarching Principal or CEO in HMC membership) and Associate Members (Heads of high performing maintained schools and