The trend-explaining industry has mostly framed the rise of P.B.R. as part of an alleged ''retro-chic'' movement. Of course, iterations of retro-chic (Fiestaware, cocktail music, etc.) have bubbled through the culture for a decade or more now. A subset ''white trash'' theory links P.B.R. to Levi's (whose sales have actually fallen) and trucker hats (a fad that was revealed and snuffed out almost simultaneously, when Ashton Kutcher wore one on his MTV show, ''Punk'd''). One zeitgeistmeister has even suggested that P.B.R. drinkers were inspired by the blue-collar heroes of 9/11.

A person who has put a lot of thought into P.B.R. is Alex Wipperfürth, of a San Francisco marketing boutique called Plan B, whose clients have included Napster and Doc Martens. He has a particular interest in brands whose identity is created not by their owners but by consumers. Plan B did a little consulting work for Pabst last year, and Wipperfürth includes P.B.R. in a book he's completing called ''Brand Hijack.'' To Wipperfürth, P.B.R., a long-withered brand, had few negative connotations. A false rumor that Pabst was about to go out of business (untrue) worked for some as a ''rallying cry.'' P.B.R.'s scarcity, and its cheapness, also helped make it an ''underground darling.''

The single key text in Neal Stewart's codification of the meaning of P.B.R. is the book ''No Logo,'' by the journalist Naomi Klein. Published in 2000, ''No Logo'' is about the incursion of brands and marketing into every sphere of public life, the bullying and rapacious mind-set that this trend represents and evidence of a grass-roots backlash against it, especially among young people. Klein's view is that this would feed a new wave of activists who targeted corporations. Stewart's view is that the book contains ''many good marketing ideas.'' He says it ''really articulated the feelings, the coming feelings, of the consumer out there: eventually people are gonna get sick of all this stuff'' -- all this marketing -- ''and say enough is enough.''

In these circumstances, the thinking goes, P.B.R. needs to stay neutral, ''always look and act the underdog'' and not worry about those who look down on the beer, presumably because they're snobs whose negative opinion only boosts its street cred. The Plan B analysis even says that P.B.R.'s embrace by punks, skaters and bike messengers make it a political, ''social protest'' brand. These ''lifestyle as dissent'' or ''consumption as protest'' constituencies are about freedom and rejecting middle-class mores, and ''P.B.R. is seen as a symbol and fellow dissenter.'' Eventually all of this sounds like satire, but the punch line is that it isn't really that far off from P.B.R.'s strategy.

In theory, a company that discovers one of its products has started growing of its own accord could simply do nothing. But it's hard to do nothing. Especially for marketers. For P.B.R. it was clearly important to at least appear to be doing as little as possible. This is one reason that a traditional response to the discovery that ''alternative people'' were buying the beer in Portland -- taking out ads on local alt-rock stations -- was nixed. It's one reason that when Kid Rock's lawyer came sniffing around to work an endorsement deal, Pabst said no. It's one reason that the company has passed on the chance to back a major snowboarding event or to sponsor an extreme athlete. It's one reason that even upbeat five-year plans for where the brand may go envision no television advertising at all.

When Stewart talks about the small-scale projects the brand has been involved in, he constantly uses words like ''organic'' and ''genuine'' and phrases like ''let the consumer lead the brand.'' All marketers do that, but it's striking how many of P.B.R.'s mini-relationships were initiated by the representative of some subculture approaching Pabst. Stewart didn't court the bike messengers of Portland; one of them approached him. Later he started hearing from messenger groups in New York and elsewhere. Other sponsorship requests were relayed to him through contacts at underground-ish magazines like Vice and Arthur. Each little sponsorship effort -- skateboard movie screenings, art galleries, independent publishers -- expands the network.

P.B.R. was starting to sound like some kind of small-scale National Endowment for the Arts for young American outsider culture, which seemed pretty cool, although not quite a marketing strategy. But think back to the notion of P.B.R. as a somehow ''political'' brand. It's a cliché to say that political parties operate like marketers. But here it's marketing that is like politics. When Pabst provides direct support to the subcultures that first embraced P.B.R., it is shoring up its new base. The brewer still needs the swing voters -- beer buyers whose loyalty is up for grabs, and who may latch on to a hot-button brand -- and hopes that its conspicuously cool base will influence them. But without the base, the whole structure comes down.