DANIELLE HAIM is enjoying a day off in New Orleans with her sisters, Este and Alana. Together, the three make up the band Haim, and their first album Days Are Gone just entered the UK charts at number one (it made a not-too-shabby US debut at number six). They're still reeling from the strangeness of it.

"We were in and out of London for a month, going all around Europe doing promotion," Danielle says. "We literally left the day after the record came out, so now it all feels like a weird dream, because we're not there—we're back in America. It's a very surreal kind of feeling, but we couldn't be happier."

Days Are Gone is a compulsively listenable confection, an alternately cool and giddy string of songs designed to tumble effortlessly across radio waves and out of speakers. The buzz around Haim (pronounced "HY-um") has been percolating steadily for over a year—and the sisters are already industry vets, despite ranging in age from 21 to 27—but there's still something sudden about how well these songs are realized, how immediate and amiable the sisters sound. The fussed-over corners of Days Are Gone have been carefully concealed; what's left is a delirious and smart record.

It's no fluke. Este, Danielle, and Alana have been playing together since childhood, and they grew up performing with their musician parents in the family band Rockinhaim. "My dad was a drummer and we all started playing drums very young—that was each of our first instruments," Danielle says. "And then we all went to piano, and Alana kind of stuck with piano. My mom's a guitarist, and she taught us all guitar. Bass was actually the one instrument where Este was like, 'It's mine! No one else can play bass!' How Este tells it—and I don't remember this because I was so young—but apparently she didn't really like guitar that much, and my dad thought, okay, a bass has four strings, and you don't have to play chords, it's just a one-note thing. My dad was a big Talking Heads fan, and a big Tina Weymouth fan, and he just bought a bass on a whim, and Este really took to it really well."

Somehow, the sisters were able to sidestep most forms of sibling rivalry, despite sharing similar interests growing up. "We're all three years apart, so we're all pretty close in age," says Danielle. "And fighting was just kind of not—I mean, we'd get into tiffs here and there, but fighting was not something our parents were down with. We were in a family band, and we were all very, very close growing up. We each had our own rooms, but closing our bedroom doors—we never did that. Everything was always open in our house. It was never competitive. People think that we're lying when we say that, but I feel like if you get to know us, you get the vibe."

With the Haim sisters putting up a united front, Days Are Gone is a family affair, but never an insular one. The comparison I keep wanting to make is Wilson Phillips, but with actual good songs. "The Wire" transforms the arena-sized handclap of the Eagles' (otherwise dreary) "Heartache Tonight" into a clever, rapid-fire anthem suitable for 2013, with each sister taking a turn on lead vocals. "Don't Save Me" is a tumultuous, dance-ready dazzle, with a cameo by the "Glory Days" roller-rink organ during the chorus. And "Honey and I" is a nectar-sweet love song in the manner of Christine McVie.

While some of the production on Days Are Gone contains echoes from the past, the album's palette is diverse enough so that a single influence doesn't overshadow. "It's not something we really thought about—like, let's do, like, a retro thing," says Danielle. "There are certain aspects of '80s production we really like, and certain drum machines from the '90s we just like. And we grew up in the '90s. I love a fucking gated reverb drum sound, I'm sorry. I don't know if we're going to go there on the next record, but at the time we were really inspired by that shit—a lot of analog sounds, and a lot of vintage synths like Junos, and things that just fit with what we were writing and what excited us at the time. It definitely wasn't a conscious thing, but I think it was what we were feeling at the time, and what we reacted to when we heard it."

Now the sisters are ready to see the US together. "I've been to Portland with Jenny Lewis once, and it was fucking awesome," Danielle says. "I can't wait to tour America with my sisters, because I've done it so many times with other people and I'm just excited to play, you know. And to just keep doing what we're doing, honestly. It's been the craziest ride so far, and the record just came out, so we want to continue writing and recording and keep going."