Densa was originally a fictional association created in parody of Mensa International. Rather than belonging to the smartest 2% of the population (the criteria for membership eligibility for Mensa), members of Densa must be in the stupidest 98%. The name Densa is a portmanteau of dense (with the meaning stupid) and Mensa.
There is no single formal Densa organisation; instead, various projects using that name exist as informal groups, usually meant by their founders as a joke rather than a serious organisation. Even within Mensa itself, a SIG (special interest group, an informal sub-group of Mensans sharing a particular common interest) has existed for Densa; which, like all Mensa SIGs, required Mensa membership for admission, while it was active.
The concept of an organization for the mentally dense originated in "Boston & Outskirts Mensa Bulletin (BOMB)", August, 1974, in "A-Bomb-inable Puzzle II" by John D. Coons. The puzzle involved "The Boston chapter of Densa, the low IQ society." Subsequent issues had additional puzzles with gags about the group, and were widely reprinted by the bulletins of other Mensa groups, before the concept of a low IQ group gained wider circulation in the 1970s, with other people creating quizzes, etc.
- Boxer, Sarah (1999-11-13). "What's the Opposite of a Tree? Ask the Testers at Mensa's Gate.". The New York Times. pp. B13. "There is a special club for those who don't make it into Mensa, the high IQ society. It is called Densa (really)."
- Queenan, Joe (1989-03-28). "You Wanna Be a Wacko, You Gotta Pay the Dues.". The Wall Street Journal (Eastern edition). p. 1. "Says Densa is one of many groups who are "the wacko patrol: the daffy, satirical organizations that never fail to tickle our funny bone with their zany antics.""
- Ward, Bruce (1999-05-17). "At Last: Mensa for Dummies". The Ottawa Citizen. Available on Lexis-Nexis.
- Fisher, Sophie (1982-01-29). "Think You're Dumb? Densa Will Help You Find Joy in Stupidity". The Globe and Mail. Available through Lexis-Nexis.
- "Genius is as Genius Does". St. Louis Post-Dispatch. 1995-01-17. Available through Lexis-Nexis.
- Amyx, Meredy (June–July 2005). Lundeen, TJ, ed. "The Origin of Densa". Interloc, a publication of American Mensa, Ltd. Retrieved 2007-06-28.
- Price, Stephen; Shields, J. Webster (December 1983). The Densa Quiz: The Official & Complete Dq Test of the International Densa Society. Avon Books. p. 64. ISBN 978-0-380-85563-6.
- McGowan, William (1987-08-23). "A Sense of Belonging". The New York Times. Retrieved 2007-06-28.Not available through New York Times archival service, but available through ProQuest.