Mensa is the most well-known high-IQ society in the world. It discriminates at the 98th percentile of the general population, meaning that accepts what is essentially the top "1 in 50" in general intelligence as measured by a standardized IQ test.
Mensa 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 standardized, supervised IQ or other approved intelligence test. Mensa is formally composed of national groups and the umbrella organization Mensa International, with a registered office in Caythorpe, Lincolnshire, England. The word mensa "table" in Latin, as is symbolized in the organization's logo, and was chosen to demonstrate the round-table nature of the organization; the coming together of equals.
Roland Berrill, an Australian barrister, and Dr. Lancelot Ware, a British scientist and lawyer, founded Mensa at Lincoln College, in Oxford, England, in 1946. They had the idea of forming a society for very intelligent people, the only qualification for membership being a high IQ. It was to be non-political and free from all social distinctions (racial, religious, etc.).
American Mensa was the second major branch of Mensa. Its success has been linked to the efforts of its early and longstanding organizer, 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. 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 131.
Mensa also has its own application exam, and some national groups offer alternative batteries of tests. These exams are proctored by Mensa and do not provide a quantified score; they serve 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.
Mensa's constitution lists three purposes: "to identify and to foster human intelligence for the benefit of humanity; to encourage research into the nature, characteristics, and uses of intelligence; and to provide a stimulating intellectual and social environment for its members".
To this end, the organization is also involved with programs for gifted children, literacy and scholarships, and it also holds numerous gatherings.
Mensa International consists of more than 110,000 members in 50 national groups. 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. The largest national groups are American Mensa, with more than 56,000 members, British Mensa, with about 23,500 members, and Mensa Germany, with more than 10,000 members. Larger national groups are further subdivided into local groups. For example, American Mensa has 134 local groups, with the largest having over 2,000 members and the smallest having fewer than 100.
Members may form Special Interest Groups (SIGs) at international, national, and local levels; these SIGs represent a wide variety of interests, both commonplace and obscure, ranging from motorcycle clubs to entrepreneurial co-operations. Some SIGs are associated with various geographic groups, whereas others act independently of official hierarchy. There are also electronic SIGs (eSIGs), which operate primarily as e-mail lists, where members may or may not meet each other in person.
The Mensa Foundation, a separate charitable U.S. corporation, edits and publishes its own Mensa Research Journal, in which both Mensans and non-Mensans are published on various topics surrounding the concept and measure of intelligence. The national groups also issue periodicals, such as Mensa Bulletin, the monthly publication of American Mensa, and Mensa Magazine, the monthly publication of British Mensa.
Mensa has many events for members, from the local to the international level. Several countries hold a large event called the Annual Gathering (AG). It is held in a different city every year, with speakers, dances, leadership workshops, children's events, games, and other activities. The American and Canadian AGs are usually held during the American Independence Day (4 July) or Canada Day (1 July) weekends respectively.
There are also smaller gatherings called Regional Gatherings (RGs) held in various cities that attract members from large areas; the largest in the United States is held in the Chicago area around Halloween, and features a costume party for which many members create pun-based costumes.
In 2006, the Mensa World Gathering was held from 8–13 August in Orlando, Florida to celebrate the 60th anniversary of the founding of Mensa. An estimated 2,500 attendees from over 30 countries gathered for this celebration. The International Board of Directors also had a formal meeting there. In 2010, a joint American-Canadian Annual Gathering was held in Dearborn, Michigan, to mark the 50th anniversary of Mensa in North America; this is one of several times the US and Canada AGs have been combined. Other multinational gatherings are the European Mensas Annual Gathering (EMAG), and the Asian Mensa Gathering (AMG).
Since 1990 Mensa has also sponsored the annual Mensa Mind Games competition, whereat the Mensa Select award is given by American Mensa to five board games that are "original, challenging, and well designed".
Individual local groups and their members also host smaller events for members and their guests. Lunch or dinner events, lectures, tours, theatre outings, and games nights are all common.
Some Mensa groups publish members-only newsletters or magazines, which include articles and columns written by members, and information about upcoming Mensa events. Examples include the American Mensa Bulletin, the British Mensa magazine, and the Australian TableAus.
Mensa International publishes an International Journal, which "contains views and information about Mensa around the world". This journal is generally included in each national magazine.
Mensa also publishes the Mensa Research Journal, which "highlights scholarly articles and recent research related to intelligence". Unlike most Mensa publications, this journal is available to non-members.
All national and local groups welcome children; many offer activities, resources and newsletters specifically geared toward gifted children and their parents. Both American and British Mensa's youngest members joined at the age of two. The current youngest member of Mensa is Adam Kirby, from Mitcham, Surrey, UK who was invited to join at the age of 2 years and 4 months and gained full membership at the age of 2 years 5 months. He scored 141 on the Stanford-Binet IQ test.
American Mensa's oldest member is 102, and British Mensa had a member aged 103.
According to American Mensa's website, 38 percent of its members are baby boomers between the ages of 51 and 68, 31 percent are Gen-Xers between the ages of 27 and 48, and more than 2,600 members are under the age of 18. There are more than 1,800 families in the United States with two or more Mensa members. In addition, the American Mensa general membership is "66 percent male, 33 percent female". The aggregate of local and national leadership is distributed equally between the sexes.