The then-all male Alfalfa Club held their annual dinner at the Capitol Hilton in Washington, D.C. on Jan. 30, 1993. Members of the club are seen here socializing in the lobby of the hotel. (Photo by Annalisa Kraft / The Washington Post)

On Saturday night, a room at the Capitol Hilton will fill with tuxes and evening gowns and the power players who love them. It’s the annual gathering of the Alfalfa Club, that bulwark of old-school schmoozing, forever impervious to modern conventions, such as selfies or business-casual dress codes.

The only thing richer than the lobster bisque will be the tycoons pressing the flesh with Supreme Court justices and Senate committee chairmen. Basically, this is a party you’ll never crash.

So what’s going on in there? Good question. Here’s what you need to know:

Who are these people?

Some of the richest and most powerful people in the world. The Alfalfa Club is more exclusive than most of Washington’s social organizations, and unlike, say, the Gridiron (which is all journalists), the members come from all sectors. Among the some 200 members, there’s a good contingent of political types (from both parties, but mostly senators; House members are kind of considered plebs in this crowd), and a heavy presence from the corporate world.

To name a few: Warren Buffett, Michael Bloomberg, Bill Marriott, Steve Case, Chief Justice John Roberts, White House senior advisor Valerie Jarrett, George H.W. Bush, George W. Bush, Dick Cheney, Sandra Day O’Connor, Colin Powell, Madeleine Albright and Vernon Jordan, per this excellent profile of the club by our colleague Roxanne Roberts.

What does the name mean?

The perhaps apocryphal story of the 102-year-old club’s founding goes something like this: It began as a celebration of Gen. Robert E. Lee’s birthday, and the name comes from the plant known for being “thirsty” (i.e., it likes to drink, just like some members of the club).

How do you get into the club?

Shocker — it’s invite-only! Openings occur when members die, and a group of the club’s senior members propose and approach prospective newbies. “Lobbying for admission is frowned upon,” Roberts says.

What happens at the dinner?

Each member brings two guests, who sometimes include a Hollywood type for novelty’s sake — but this is no celebrity-overrun White House Correspondents Dinner. There are funny speeches (that is, if you get inside jokes about Cabinet secretaries and the stock market) by the incoming and outgoing presidents of the club, as well as by a member held forth as the club’s mock presidential nominee.

Traditionally, POTUS shows up, though President  Obama has attended only twice: in 2009 and 2012. It’s all ostensibly off-the-record, though some of the quips and details inevitably leak.

Isn’t it just a bunch of old white guys?

Sort of, though diversity and the number of women in the club’s ranks has grown since ladies were first admitted in 1994, a move partly prompted by President Bill Clinton’s snub the previous year. Today, the roster includes businesswoman Catherine Reynolds, Sens. Kelly Ayotte and Dianne Feinstein, and Lockheed Martin chief executive Marillyn Hewson.

Alfalfa Club members apparently don’t care about looking like a bunch of elitist fat-cats, because they swear that’s not what the annual gathering is about. “Occupy Wall Street” protesters showed up in 2012 and glitter-bombed attendees, but the dinner-goers shrugged it off, Roberts reports.

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