Auslanders may view Oktoberfest as an annual piss-up in funny outfits, but for Germans, Wiesn—so called after the central-Munich park Theresienwiese, where it’s been held since 1810—is a more significant affair.

First of all, it’s technically not a beer festival, thank you, but a folk festival. Oompah music, Bavarian food, and what you wear (lederhosen, dirndls) are as important as the brew, and with more than six million visitors a year over 16 days in September and early October, it is the largest folk festival in the world.

For business executives, who book tables at the halls at least six months in advance, Wiesn is also the biggest networking event of the year. Groups from German corporations like Siemens and local branches of major multi-nationals like Philip Morris and Tiffany & Co. toast annual earnings over roast duck and tankards filled with Dom Pérignon. Just last week, Amazon sent a group of its Seattle-based executives to enjoy the festivities.

Leaning In

A by-invitation-only women’s lunch on Wiesn’s first Monday gathers a thousand or more of Germany’s female power elite, politicians and business executives. It’s a chance to see a lot of Chanel 2.55 bags with dirndls. “The network here is really special,” says Carina de Beauval Saxlund, V.P. of retail sales for Wirecard, a German financial-services provider. “It’s not just business advice you come for, but life advice. You need a divorce attorney? Ask one of the ladies here.”

Drinking at Wiesn is certainly encouraged—higher-alcohol-content recipes are created especially for the occasion and served in one-liter tankards—but the difference in how visitors approach it is apparent the minute you deplane at the Munich airport. Lederhosen are everywhere, like a deerskin forest that only goes waist high, but it’s just the natives who dispense with the giggling selfies. They act born to the look because they are.

Tracht, the Alpine and Bavarian costume that includes lederhosen for men and dirndls for women, was developed in the 19th century and hasn’t changed much since. (Hitler mandated some streamlining of the dirndl, but the general pastoral spirit has stayed the same.) No one but the Austrians wear it with any frequency during the rest of the year, but don’t you dare call it kitsch. With few exceptions, Germans don’t wear their tracht to find ironic distance from anything. There is room for personal variation, especially among women, but unlike Halloween costumes, which represent an escape from daily existence, one’s dirndl tends to follow one’s taste at lower altitudes. Someone opting for a stonewashed-denim apron with Swarovski crystals is likely already a frequent shopper at Forever 21.

Fair Ground

Despite setting aside the first Sunday for Rosa Wiesn, a gay get-down, Wiesn and its trappings are not here to evolve. Quite the opposite. Detractors might thus accuse the celebration of suffering from the same disease as German industry and politics: resistance to change.

Gloria von Thurn und Taxis serenades the crowd.

The biggest brewing companies in Germany, like Löwenbräu, Paulaner, and Augustiner, erect wooden dining halls, many with a capacity of thousands. Rather than take each year as a new branding opportunity, as would be de rigueur for major industries in New York, London, and Paris, the companies design the halls (colorful streamers or painted chalet-style) and menus (roast chicken, beef stew, and weisswurst) in the same way they have since the doors first opened: safe, nostalgic, happy, high calorie. For families, who come in droves, Wiesn is an intergenerational day out at the fair, with carnival rides and strudel stands until dark. Then it’s run along home before the tourists and students go into binge-and-purge mode.

Hitler mandated some streamlining of the dirndl, but the general pastoral spirit has stayed the same.

Wiesn is the biggest business hustle-cluster of the year. Canny planners know to schedule outside dos for late September, hoping the festival will help lure a technology fair like Bits & Pretzels, where Barack Obama gave the keynote speech this year. DAB BNP Paribas could schedule their investment congress anytime they wanted, but cold figures go down better with suds.

You’ll often find the executive schmoozers in the two poshest halls, under the shadow of the park’s massive bronze statue of Bavaria. Käfer Wiesen-Schänke serves roast duck and tankards full of champagne, and Schützen-Festzelt’s straightforward Bavarian fare comes with optional magnums of Dom Pérignon. Corporate titans mingle with Bayern München football stars, retired politicians, and Boris Becker and his latest ex-wife. The men tend to be middle-aged, and the women tend to be young.

Like any Shriners’ convention worth its salt, the hair comes down with the sun. That’s when Arnold Schwarzenegger, in full gear, finally breaks a sweat from glad-handing at the Marstall Festzelt, and Gloria von Thurn und Taxis, one of only a handful of women this year to refuse a dirndl, jumps onstage to rock out with Käfer’s house band. (She plays bass.)

Queen Regine

Even genuine signs of progress follow a prescribed etiquette. In a country where only 46.5 percent of women are in the workforce, Regine Sixt’s Damenwiesn, in the Schützen Festzelt, is a signal event. Sixt, who at (officially) 69 is still the face of the German car-rental business, is the creator and host of the lunch. To attend the event, you have to be invited, and you have to make a sizable donation to Regine’s Tränchen Trocknen (Drying Little Tears) children’s foundation.

Regine Sixt’s luncheon at Oktoberfest has become the largest women’s networking event in Europe.

“Germans are very humble and don’t want to call it ‘networking,’ as if the association with personal business success would detract somehow from the charity,” says Yaiza Armbruster, a Munich-born and New York–based interior designer who is attending Regine’s Damenwiesn with a group of female family friends. “But it’s definitely a networking event.” Armbruster is one of the #oldceline faithful, so delicate pin-tucking and silver buttons are her dirndl’s only real adornment. But there is plenty of blingy diamond jewelry reflected in the bright overhead lighting as the invitees take their seats. Among them are politicians like Dagmar Wöhrl, a retired longtime congresswoman, and Ilse Aigner, the president of the Bavarian legislature, and real-estate bigwig Renate Thyssen-Henne. And they are all in aprons.

There is plenty of blingy diamond jewelry reflected in the bright overhead lighting.

Iris Brand, head of communications for Philip Morris in Germany, was invited for the first time this year. “It’s an honor,” she says. “There are only high-class ladies, from all kinds of business. That’s what makes it interesting.”

After everyone is finished mingling and starts in on their cheese boards and pretzels, Regine Sixt emerges. “Every woman in here is a Bavarian goddess!” she shouts to cheers. Diminutive but fearsome, she sets personal assistants running with a twirl of her finger. (She’s effective, however: Drying Little Tears is funding 175 projects, from music lessons in Italy to schools in Nairobi, in more than 50 countries worldwide.) As the plates of roast chicken are distributed—crispy-skinned and spit-roasted, it is the truly traditional Wiesn grub—a D.J. spins Munich Sound disco.

“Every woman in here is a Bavarian goddess!”

Once the plates are cleared, the live entertainment commences. Bernie Paul, now in his late 60s, takes to the stage to perform the 1970s club hit “It’s a Real Good Feeling.” This gets the ladies out of their chairs and onto the tables. Everyone sings along. Braids come down, where they will stay until the aperschnalzen dancers emerge, cracking whips in time to the accordion.

Apple C.E.O. Tim Cook gets in on the action.

Sixt remains in charge of international marketing for Sixt, one of the largest car-rental companies in Europe. She’s been holding the event for more than 20 years. “It all started as a ladies’ lunch for some American girlfriends,” she says, “and then it got bigger and bigger, so I thought, ‘Why not make it even bigger?’ Female networking is not so normal in Germany.”

It’s a gesture of sisterhood for a woman who is a living example of the dynamic executive: Sixt is a local consul to Barbados, was the first woman and first non-Jew to be named a Hadassah International Citizen of the World—for her work with charities in Israel—and still shows up to the office every day in a company with more than 5,000 locations in 105 countries. But she is unconcerned with today’s feminism. “What’s my advice for young businesswomen? Stay a woman,” she says. “My husband is king. I was lucky, but I can see it’s often difficult for women to work and be mothers at the same time.”

“What’s my advice for young businesswomen? Stay a woman. My husband is king.”

It’s the kind of line that might appeal to Kristina Frank, a candidate with the conservative C.S.U. party for mayor of Munich. Running on a quality-of-life platform, she has been spotted all over town campaigning in a bicycle rickshaw, a pedal-powered local version of the Straight Talk Express. On Monday, she parked it, popped on her dirndl, and paid her respects to Regine.

Alexandra Marshall is a writer based in Paris. Anne Philippi is a writer based in Berlin