Twenty years ago, few outside Yale’s walls even knew they existed.

Yale’s now infamous secret societies once truly lived up to their billing as autonomous, anonymous brotherhoods of campus and future leaders.

Today, their names and locations are common knowledge, newspapers have analyzed their million-dollar tax records, they’ve inspired Hollywood movies, their alleged initiation rituals have graced television news broadcasts, and most have gone coed — but much about Yale’s secret societies is still very much a mystery.

For most students, the societies, with names like Scroll and Key, Berzelius, Book and Snake and, of course, Skull and Bones, are more the objects of amused speculation than they are a force to be reckoned with.

Dating back to 1832 — the year Yale seniors Alphonso Taft 1833 and William Huntington Russell 1833 founded the Order of Skull and Bones — societies have prided themselves on their ability to make world leaders, control Yale’s top athletic and extracurricular offices, and, most of all, shroud themselves in secrecy.

Despite increased public scrutiny — including the recent airing on World News Tonight of a videotape of what ABC alleged to be Skull and Bones’ initiation rituals — many parts of society life, including much of what goes on at the organizations’ weekly meetings, remain an enigma.

Every member of Skull and Bones, Yale’s most famous secret society, is assigned a Sunday night during which to tell his or her life history to fellow members who are sworn to secrecy, history professor Gaddis Smith said.

Members also have “Connubial Bliss” nights during which a member divulges all sexual experiences to fellow Bonesmen, Smith said.

Skull and Bones is said to be a force behind the Central Intelligence Agency and the maker of three U.S. presidents.

William Howard Taft 1878, George H.W. Bush ’48 and George W. Bush ’68 were all “tapped” to enter the society for their senior years at Yale.

Like a startling number of his fellow Bonesmen, George H.W. Bush also served in the CIA.

So many Yalies once took jobs with the agency after graduation that government officials commonly joked that Yale’s famous “Whiffenpoof Song” was the CIA’s anthem.

Many societies, including Skull and Bones, make their homes in “tombs” — huge, windowless stone crypts that dot Yale’s central campus.

Skull and Bones’ property and tomb, located at 64 High Street just off Yale’s Old Campus, have been assessed by New Haven tax officials at $716,000.

The oldest societies receive funding from parent organizations with names like the Russell Trust Association, Inc., which operates Skull and Bones, and the Kingsley Trust, which operates Scroll and Key.

The societies are not exactly the stuff of the recent Hollywood film “The Skulls,” but they do have million-dollar endowments.

As of June 30, 1998, Skull and Bones owned, via the Russell Trust, more than $3,674,000 in assets.

In the end, the closest most Yalies will ever come to Skull and Bones is “Tap Night” — the annual April event where most of the societies select a small number of juniors to join their ranks.

Skull and Bones selects only 15 students each year, drawing heavily from the ranks of Yale’s fraternity leaders and athletic captains.

Unlike Tap Night for freshmen rushing Yale’s many a cappella groups, there are no loud celebrations on Old Campus or whole-hearted congratulations from friends on secret society Tap Night.

One night every spring, society members roam campus in black robes and masks, looking for juniors to form their next generation. New members are taken away quietly into the silence of the night and sworn to secrecy about the world they are about to enter.

Little is known about what societies do with their initiates.

If you luck out, three years from now you just might find out.