A high-IQ society is an organization that limits its membership to people who have attained a specified score on an IQ test, usually in the top two percent of the population (98th percentile) or above.
[1][3] The largest and oldest such society is Mensa International, which was founded by Roland Berrill and Lancelot Ware in 1946.
[4][3] High-IQ societies typically accept a variety of IQ tests for membership eligibility; these include WAIS, Stanford-Binet, and Raven's Advanced Progressive Matrices, amongst many others deemed to sufficiently measure or correlate with intelligence.
Tests deemed to insufficiently correlate with intelligence (e.g. post-1994 SAT, in the case of Mensa and Intertel) are not accepted for admission.
Since the 1960s, Mensa has experienced increasing competition in attracting high-IQ individuals, as various new groups have emerged with even stricter and more exclusive admissions requirements.