Is indie rock a sound, an attitude or a popular website? This year's Pitchfork Music Festival [ tickets ] in Chicago made a case that it is all three--a lifestyle, even.

The popular, Chicago-based online publication Pitchfork is a steadily influential voice and brings what was once an underground counterculture closer to the mainstream. Recent minor-hit groups such as The Arcade Fire or Clap Your Hands Say Yeah owe much of their success to Pitchfork's critical championing of a classic indie sound: melodic but sometimes heavy guitar, dramatic dynamic changes and wordy, sometimes heady lyrics.

This year's festival will be closely compared to the Vice Records-curated Intonation Festival, which took place June 24-25. Last year, the fests were one, but there was a falling out. In the end, Chicago reaped the rewards with two very different--but equally worthwhile--two-day blowouts closing in on the monster Lollapalooza, which takes place this coming weekend.

Pitchfork's programming of proven indie-rock favorites and cult acts--some of whom have more than six albums out and could fill small auditoriums by themselves--resulted in much healthier ticket sales ($30 for a two-day pass) than Intonation, and both days of the Pitchfork fest were sold out to the tune of 17,000 bodies.

And, unlike this year's Intonation, which was blessed with mild, sunny weather, Pitchfork's weekend was hot and sticky. The mercury was well over 90 by 1 p.m., when Hot Machines, a three-piece Chicago garage supergroup (featuring members of The Ponys, Miss Alex White and The Red Orchestra, and Baseball Furies) took the stage. The Ponys just signed to venerable indie Matador, but the Hot Machines are leaner, meaner and a bit more engaging live.

Each day, the first four bands to appear on the two main stages got roughly a half-hour, and the next seven got about an hour. It's easily possible to see all the alternating main-stage acts, but the action at the Biz 3 (a Chicago-based PR and marketing company that works with electronic, hip-hop oriented acts) tent overlapped. At the sweltering tent, local superstar DJ duo Flosstradamus scratch tested in one of the day's longer soundchecks. And once things got rolling, it wasn't exactly a staggering, hands-in-the-air success at first, as the fellas are more suited to midnight start times, but it was a chance to dance.

Man Man really kicked things into gear. Sporting tennis whites and prodigious facial hair, the oddball outfit used frantic percussion, melodica and brass to augment rollicking, almost Vaudeville-esque electric piano and vocals (which sounded a bit like Glenn Danzig or Tom Waits at times). The band jumped, squawked together and threw brightly colored feathers at the audience.

One of the fest's most talked about bands, Band of Horses [ tickets ], took the stage rather early. Having flown in from Seattle in the middle of the night, the group looked tired, but moved with ease between delicate guitar rock and ecstatic moments. The band's soaring music is grand, but its attitude nonchalant. "I think it's hot because of the temperature and the heat ... so far I've noticed," offered singer Ben Bridwell before saying goodbye with, "We're Band of Horses, or something."

The Mountain Goats [ tickets ] have earned a cult following for the songwriting of John Darnielle, who smiled intensely and made in-jokes--"please pogo to my jam"--and talked about the test pressings of his first vinyl single as he played with a bassist and sometimes guest keyboardist songwriter/critic Franklin Bruno. Darnielle's tunes use a sparse number of chords but lots of words, which some folks up front knew by heart. Another lover of words, Dan Bejar, led a five-piece band into the most delicate arrangements of the day. Sometimes moody, sometimes jangly, then frenetic, Destroyer was a bit of a nice surprise in a live setting. And the quips weren't bad, either. Singer: "A quarter of that one is a protest song." Guitarist: "Protesting the other 3/4s of the song?"

Tim Tuten, from Chicago club the Hideout, was the main stage MC and introduced most of the bands. He gave Art Brut a rousing intro, quoting its tunes: "Your little brother just discovered rock and roll. Art Brut--Top of the pops!" The British quintet stole the stage back with "Formed a Band," as Eddie Argos sported colorful socks and excellent banter; one guitarist looked like a New York Doll and the other wore extremely tight trousers. Argos hop-scotched on his mike cable and, at one point, explained that a new tune was "about my brother again and drunken text messaging."

While Matmos brought a virtual laboratory of hardware and guitar to stage for a set of gurgling and clicking sounds, the main stages soon picked up tempo. Ted Leo and the Pharmacists started with the arpeggiated riff of "Little Dawn," and then tested some new material amid album tracks that Chicago fans have heard many times before. The Walkmen, touring on their best album yet, made use of Tambourine, organ or piano, and thumping floor tom on tunes like "Louisiana." But the night peaked with The Futureheads, who maintained insane tempos, drew the massing audience in with hand-claps and singalongs (for "Hounds of Love"), all while wearing clothing (a sweater vest!) clearly not meant for summer. In the twilight, "Favors for Favors" found the guys bringing together choppy guitars, unusual accents and bettering any of the band's recordings. A frenetic mess of a tune "about the Scandinavian warriors who came over to the northeast of England and made us a helluva lot taller" balanced the ulra-poppy "Skip to the End," making The Futureheads the night's big winners.

Silver Jews (who've been around for 15 years but never toured until now) were tuned up with 13 minutes before start time. Even with indie vets Duane Denison and Pernice Brother Peyton Pinkerton playing guitar as Berman strummed, the Jews are a sleepy or just plain boozy affair. A-Trak in the Biz 3 tent caused more commotion, combining samples of GN'R and Journey, dirty south a cappella vocals with looped dance rock rhythms, and Young Jeezy's big hit. At 9:50 p.m., the Jews announced the last tune but played two more, going off the rails as Berman chants "I Saw God's Shadow on this World." By show's end, it's obvious that the Jews have nothing to be embarrassed about, except poor scheduling. They're not headline material.

Day 2 wasn't any milder weather-wise and was front loaded with buzz bands Tapes 'n Tapes at 1 p.m. on the main stage and a jazz set from fret-burning Jeff Parker-Nels Cline Quartet on the Biz 3 stage. But it was a 1:55 Biz 3 stage debut from the DJ/rapping threesome Bonde do Role from the south of Brazil that made the most lasting impression. With a crammed tent of curious fans (and the smattering of Brazilians that were in attendance), the group put on a baile funk version of the "Final Countdown" and ran through a number of hooky loops (Tone Loc's "Wild Thing" and Kraftwerk's "The Model") while rapping playfully. Singer Marina dove into the crowd, body surfed for a minute and returned to the stage, but landed wrong on the stage monitor on her return. Seconds later, she was in agony 30 yards away. Her band quickly replaced her with the girls from CSS (the Brazilian electro-punk-pop tourmates) to complete the set for the fest's most spontaneous moment.

Sao Paulo once had a new wave underground of its own, but the girls in CSS don't need to know that. The Biz 3 tent was jammed (as it was nearly all day), and the band ripped through its new-wavey, three-chord wonders with amazing enthusiasm and amateur charm.

Back on a main stage, The Liars' singer Angus Andrew made it clear what a now Berlin-based, deconstructed band playing deconstructed punk sounds like: Krautrock, basically. He howled, played minimal notes, and often let two drummers pound out dense beats for minutes on end. He also managed to remove his shirt and black pants to reveal a blue outfit that could be a dress or a smoking jacket, but not much else. The sonics went from spectral to cacophony.

The Pitchfork fest isn't the picture of diversity. Brazilians outnumber African-Americans on stage, but Aesop Rock and Mr. Lif's set was a welcome change. The wordy, sometimes-political rappers tag-teamed on dense rhymes. But Mission of Burma's first tune, "That's How I Escaped my Certain Fate," might have been the most explosive moment of the day. It was a raging hour for the elder statesmen of the scene.

With a Diplo DJ set coming up, space in the Biz 3 tent (or outside of it) was non-existent and when the Philly DJ played his own remix of Kanye West's "Gold Digger," it was another perfect Pitchfork moment, though one wonders when Diplo's honeymoon will end.

It was quite momentous when headliners Os Mutantes take the stage. The 10-member band came fronted by two original members and backed by the primary drummer Dinho from the legendary Brazilian psychedelic group, who've never played in Chicago. Brothers Sergio Dias and Arnaldo Baptista were in top form, though Arnaldo was a bit low in the mix. The band managed versions of "Baby," "Bat Macumba" and more. Before launching into a samba, Sergio Dias took extra time to mock another Sergio: Mendes. But for the most part, the vibe was triumphant and exuberant. Dias' smiles and fuzz-guitar excursions seemed to last just the right length of time. You'd have to be really jaded not to smile with him.