The only membership requirement for joining Mensa International is to pass an official intelligence test with a score within the top two percent of all the people who participate in that particular exam. After submitting proof of the test results, or taking an official Mensa entrance exam at a local office, applicants can pay an entrance fee to earn annual membership.
Mensa uses a percentile ranking method to determine eligibility to join its organization, rather than a single numerical value, in order to decrease confusion and simplify the process across different types of tests. In particular, Mensa seeks to avoid use of the term "IQ" due to many common misconceptions about its meaning. As such, it only requires applicants to obtain a score that is the same as or better than 98% of the general population taking that test, as long as it tests the taker's intelligence through an official recognized process.
The organization also maintains its own entrance exam that carries the same percentage qualification requirement. In order to take the test, applicants must contact a local Mensa International office to find out about the availability of testing options and make the appropriate arrangements. The test typically carries a processing fee and must take place on the premises in order to ensure its validity. The organization also requires official copies of outside test results to avoid fraud.