Punctuation is crucial to Los Campesinos!, the indie-rock septet from Cardiff, Wales.

"Knee Deep at ATP," from their recent debut album

Hold On Now, Youngster . . .

, begins by parsing the sentences spoken during a tryst at the All Tomorrow's Parties festival, making metaphors of ellipses, parentheses and "correctly used apostrophe[s]."

And that exclamation point in their name (Spanish for "the farmers" or "the peasants") is all-important: every song during their 65-minute set at Johnny Brenda's Saturday night zipped by in an exuberant rush punctuated with shouted declamations.

Los Campesinos! do have a serious side. They are admitted indie-rock snobs: They covered


Pavement songs ("Frontwards" and part of "Box Elder"), and many of their songs are self-reflexive manifestos about the music scene, with allusions ranging from Lesley Gore to K Records. And, in a nod to the tradition of the Ramones, the seven recent Cardiff University grads all use "Campesinos!" as their last name.

But little of that really mattered Saturday night.

The breathless words of Gareth and Aleksandra Campesinos! were often indecipherable amid the joyful music - a playful, hook-filled mix of hard-strummed electric guitars, buzzy keyboards, ringing glockenspiel, eight-note handclaps and thumping drums, all threaded with violin and stop-start twists and turns.

The Pavement covers brought knowing smiles to many in the packed club, but the irresistible guitar riff that anchors "You! Me! Dancing!" brought more: The title was a self-fulfilling prophecy, although the dancing consisted mainly of unfettered pogo-ing, physical manifestations of exclamation points.

The show was a caffeinated sugar-rush of controlled chaos and coed vocals, with Aleksandra Campesinos! providing a sweet-voiced anchor and Gareth Campesinos! quivery recitations, and with the rest of the band interjecting shouted exclamations and call-and-response harmonies.

By the end of the night, on "Sweet Dreams, Sweet Cheeks" and "2007, the Year Punk Broke (My Heart)," the audience was shouting along.

Another seven-piece, Philadelphia's An American Chinese, opened the show and displayed their Decemberists-like sartorial splendor and carnivalesque arrangements - xylophone, keyboards, amped-up acoustic guitars - but their melodies could have used some of the hooks-to-spare of Los Campesinos!.