Mensa International

Mensa is the largest, oldest, and best-known high-IQ society in the world. The organization restricts its membership to people with high testable IQs. Specifically, potential members must score within the top 2% (at or above the 98th percentile) of any approved standardized intelligence test. Mensa is formally composed of national groups and the umbrella organization Mensa International.
See more at Wikipedia.org...