Mensa is the largest, oldest, and most famous 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 intelligence test. Mensa is formally composed of national groups and the umbrella organization Mensa International.
The aims are to create a non-political society free from all social distinctions (racial, religious, etc.). The society welcomes all people, regardless of background, whose IQs meet the criterion, with the objective of members enjoying each other's company and participating in a wide range of social and cultural activities.
Mensa accepts individuals who score at or above the 98th percentile on certain standardized IQ tests, such as the Stanford-Binet. Because different tests are scaled differently, it is not meaningful to compare raw scores between tests, only percentiles. For example, the minimum accepted score on the Stanford-Binet is 132, while for the Cattell it is 148.
In addition to encouraging social interaction among its members, the organization is also involved with programs for gifted children, literacy, and scholarships. The name comes from mensa, the Latin word for "table", and indicates that it is a round-table society of equals (although the logo can be seen as depicting a square table, i.e. a Parsons table, with only three legs visible).
Mensa has published a number of books, including Poetry Mensa (1966), an anthology of poems by Mensans from all over the world, in which languages other than English are represented. 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.
At Mensa's 50th Anniversary, Dr. Ware, one of the founders, addressed Mensans by stating that he hoped that “Mensa will have a role in society when it gets through the ages of infancy and adolescence.” He also said, “I do get disappointed that so many members spend so much time solving puzzles,” expressing his desire for Mensans instead to be solving some of the world's problems.
Additionally, 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 cooperations, reflecting the wide diversity of members in occupation and social class. Some SIGs are associated with various geographic groups, whereas others act independently of official hierarchy. There are now quite a number of electronic SIGs (eSIGs), which operate primarily as e-mail lists, where members may or may not meet each other in person.
There are also smaller gatherings called Regional Gatherings (RGs) held in various cities that attract members from large areas; the largest is held annually in Chicago around Halloween, and features a costume ball and a joke-telling competition. Many members will arrange their vacations to attend an RG in another part of the country (such as the one in Chicago) as an annual tradition. Some members will regularly attend as many as half a dozen RGs every year.
In 2006, The Mensa World Gathering was held from August 8 to August 13 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.
The 2006 British AG was held in Nottingham between September 28 and October 2. This incorporated a birthday party to celebrate Mensa's 60th birthday on 1 October 2006 (1 October 1946 being the date that Berrill and Ware filed papers with Companies House for the society).
All national and local groups welcome children; many offer activities, resources and newsletters specifically geared toward gifted children and their parents. American Mensa, for instance, has 1,300 child members, ranging in age from 3 to 18. The youngest people who have joined the organization were both aged 2 years and nine months; the first was Ben Woods in the 1990s, the second was Georgia Brown from Aldershot, Great Britain in 2007. She was six days older than Ben Woods was when he joined Mensa. The Mensa Research Journal, which is published quarterly, includes a TAG (Talented and Gifted) Progeny section especially for younger members.
At the other extreme British Mensa had a member aged 103 According to the American Mensa site 41 percent of members are between the ages of 44 and 61 and just under 60 percent of the new members in 2004 were between the ages of 23 and 43. There are more than 1,500 families with two or more Mensa members.