Thanks to their breakout single "Little Talks" – and its four-on-the-floor remix courtesy of Passion Pit – this Icelandic six-piece, whose sound calls to mind the uplifting folk-pop of Mumford & Sons and Arcade Fire, has quickly developed a major Stateside following. Their Lollapalooza appearance marks their biggest US gig to date. The sudden global popularity that followed their debut LP, My Head is an Animal, is still shocking to the band, says co-lead singer Nanna Bryndís Hilmarsdóttir. "When we were making this album, we weren't thinking about even going out of Iceland to tour or anything like that," she says. "It's very weird. But it's wonderful."

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