(Fortune Magazine) -- Ever since August Busch IV went to work for the family business 21 years ago, speculation has swirled over whether he would someday lead Anheuser-Busch. To prove his readiness for the corner office, he's had to reach certain milestones. Master the craft of brewing: Check. Learn to market beer: Check. Grow the domestic brewing business, which accounts for almost 75% of the company's $15 billion revenue: Well - he's still working on that one.

Busch, 42, who is president of A-B's (Charts) U.S. beer biz, recently satisfied perhaps the most important qualification of all: He got married. By all accounts, "the Fourth" has the inside track to become the next king of beers. But the handsome ladies' man has long understood that he needed to marry in order to have his father, chairman August Busch III, and the board of directors take him seriously. (CEO Patrick Stokes is widely considered an extension of Busch III and a place saver. He turns 65 in 2007.)

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"That was always the quid pro quo," says one person who worked for the men. "It was, 'August, until you settle down and stop being the wild man, nothing is going to happen.' " Says another, who's more cynical: "He's really close to getting elevated. He's probably saying, 'This will help me.' "

The Fourth has a history to live down. In 1983, while a student at the University of Arizona, he had a Chappaquiddick-like accident in which he left the scene of a crash that killed a woman who had been riding in his Corvette. (He was never charged with a crime.)

And his penchant for partying is legendary. He didn't make it to Vail in late July for the Beer Institute meeting. But he sent a video message: "Sorry I couldn't be with you, but I've got a lot of wedding activities I have to attend to. Including a bachelor party - an event I've been preparing for all my life."

Who's the lucky beer princess? Kathryn Thatcher, 25, of Fairlee, Vt. They married in her home state on - get ready - Aug. 5. Will there be an August V someday? "I always wonder about that," says his aunt Beatrice Busch von Gontard. "Where's the cutoff? Or do you be like Henry VIII and just keep going?"

Assuming Busch does ascend to the CEO post, he'll have to grapple with increased competition from global brewing giants InBev and SABMiller. More generally, wine and spirits have cut into beer's market share of late. The Fourth is taking steps to address that issue and is building up the company's portfolio of crafts and imports, categories that are growing faster than mass-marketed beers. But it's going to be a tough slog. Last year Anheuser-Busch experienced an 18% drop in profits, its first dip in earnings since 1997. Hopefully, he took a nice long honeymoon to gear up for the job.

Happy hour for drinkers' wages.