Mensa International

Mensa International is the largest and oldest high-IQ society in the world. It is a non-profit organization open to people who score at the 98th percentile or higher on a standardised, supervised IQ or other approved intelligence test. Mensa formally comprises national groups and the umbrella organisation Mensa International, with a registered office in Caythorpe, Lincolnshire, England, which is separate from the British Mensa office in Wolverhampton.

The word mensa (/ˈmɛnsə/, Latin: [ˈmẽːs̠ä]) is Latin for 'table', as is symbolised in the organisation's logo, and was chosen to demonstrate the round-table nature of the organisation: the coming together of equals.

Roland Berrill, a British-Australian barrister, and Lancelot Ware, a British barrister and biochemist, founded Mensa at Lincoln College, in Oxford, England in 1946, with the intention of forming a society for the most intelligent, with the only qualification being a high IQ.

The society was ostensibly to be non-political in its aims and free from all other social distinctions, such as race and religion. However, Berrill and Ware were both disappointed with the resulting society. Berrill had intended Mensa as "an aristocracy of the intellect" and was unhappy that the majority of members came from working or lower-class homes, while Ware said: "I do get disappointed that so many members spend so much time solving puzzles."

American Mensa was the second major branch of Mensa thanks to the efforts of Margot Seitelman.

Mensa's requirement for membership is a score at or above the 98th percentile on certain standardized IQ or other approved intelligence tests, such as the Stanford–Binet Intelligence Scales. The minimum accepted score on the Stanford–Binet is 132, while for the Cattell it is 148, and 130 in the Wechsler tests (WAIS, WISC). Most IQ tests are designed to yield a mean score of 100 with a standard deviation of 15; the 98th-percentile score under these conditions is 130.8, assuming a normal distribution.

However, American Mensa does not provide a score comparable to scores on other tests; the test serves only to qualify a person for membership. In some national groups, a person may take a Mensa-offered test only once, although one may later submit an application with results from a different qualifying test. The Mensa test is also available in some developing countries such as Brazil, India, Indonesia and Pakistan.

Mensa International consists of around 150,000 members in 90+ countries, 48 of which have their own national groups. The national groups issue periodicals, such as Mensa Bulletin, the monthly publication of American Mensa, and Mensa Magazine, the monthly publication of British Mensa. Individuals who live in a country with a national group join the national group, while those living in countries without a recognized chapter may join Mensa International directly.