A tasting held earlier this summer in Brooklyn, New York, might have confused anyone accustomed to sipping genteelly from a wine glass. In the backyard of a shop, a fan strafed sweaty people sitting on folding chairs. A scruffy man in jeans and a T-shirt raised his voice above the whir to introduce the first pairing, a thimble-size tumbler of dark liquid and a bit of cheese. When glasses met lips, noses crinkled: The liquid was beer—and it was sour.

The shop, Bierkraft (“beer strength” in German), sells gourmet cheese and beer from small, independent breweries and is at the fore of a shift in American brewing. Craft beer is the fastest-growing segment in the $4 billion industry, and it’s helping change beer’s image: The rough-and-tumble tipple is now sometimes considered an after-dinner drink on par with wine and brandy.

It’s no accident that four of the five sour beers offered that evening come from Belgium (where sour beer is just a small niche in the country’s brewing scene). Belgian ales, styles taken up more recently by American craft brewers, are leading the craft-beer charge. Since January, U.S. grocery and convenience stores have sold .64 percent fewer cases of beer versus the first seven months of 2006, according to Information Resources, a Chicago-based firm that monitors sales. Meanwhile, craft-beer sales have risen, and Belgian-style ales are doing even better, with sales up almost 31 percent.

“One in three of our customers is looking to pair beer with food,” says Ben Granger, one of Bierkraft’s owners. “If a wine drinker comes in, I’ll definitely point them to a Belgian. It’s a gateway beer.”

Belgian styles are more complex—more wine-like in their subtleties—than the mass-produced German-style lagers that dominate the American market. In Germany, the Reinheitsgebot, a purity law dating from 1516, limits brewers to four ingredients: barley, hops, yeast, and water. Budweiser and the other big beer companies use rice and corn instead of barley, but with pretty bland results. The monks who traditionally brew Belgian ales, however, use fruit, spices, and other unorthodox ingredients.

“In Belgium,” says Joe Carroll, the owner of Spuyten Duyvil, a Brooklyn bar that specializes in beer and cheese, there’s a tradition of “taking some risks and doing some things that in the German or English tradition would be verboten.”

Garrett Oliver, the brewmaster at Brooklyn Brewery, thinks that Belgian beer’s stylish packaging—it often comes in corked 750-milliliter bottles—appeals to wine drinkers.

“People say that Belgian beer comes in champagne bottles,” he says, “but actually, champagne comes in beer bottles. We’ve been doing it a lot longer.”

It’s no coincidence. Both champagne and Belgian-style ale go through a fermentation process in the bottle that produces the bubbles. For champagne, this is called the méthode champenoise. Brewers know it as bottle conditioning.

Brooklyn Brewery’s newest beer, the “Belgian-inspired” Brooklyn Local 1, is bottle-conditioned; a corked, 750ml bottle costs $7 to $12—as much as a six pack of the company’s other beer. A higher price point and fancy glassware created by Belgian brewers contribute to Belgian beer’s upmarket image. It may be little more than clever marketing, but the chalices, goblets, snifters, and flutes that hold the ale are more reminiscent of wineglasses than the stocky pint glasses popular in English and American pubs. (See "The Science of Beer Glasses.")