New albums from the Kansan duo Mates of State and the Canadian sextet Islands remind us of the simple pleasures of indie pop. Both albums, out today, are small in terms of scale, but not in terms of ideas, and while a tad insular — traditional indie pop is relatively untouched by the changes and shifts of hip-hop and dance music — they’re never provincial, thanks in large part to their modesty and restraint.

Neither Mates of State nor Islands is going to crack the Billboard Top 10 anytime soon, but both acts are more interested in playing to fans in intimate clubs than for thousands who know only a solitary radio hit.

Mates of State’s “Re-arrange Us” (Barsuk Records) finds the husband-and-wife duo of Kori Gardner and Jason Hammel developing their frenetic music of almost unabashed joy. “Re-arrange Us,” the duo’s fifth album, marks the first time Ms. Gardner has abandoned her trademark organ in favor of pianos and synthesizers throughout the album.

On the group’s previous outings, Ms. Gardner’s organ — often played as if she were scoring a flying-saucer chase scene in a movie — provided an otherworldly precocity to the band’s songs, which Mr. Hammel backed with his up-tempo drumming. (Both members sing.) The result was a cutesy, emo-pop version of 1940s cartoon music (think Raymond Scott and Spike Jones) riddled with harmonies and melodies so infectiously sweet and giddy that they belonged in a candy store.

That isn’t intended as a knock: So few bands are interested in happiness in and of itself these days. But for “Re-arrange Us,” Ms. Gardner and Mr. Hammel achieve that bliss through intelligent songwriting alone. Ms. Gardner’s piano lines aren’t as manic and restless, which requires Mr. Hammel to be more tasteful and controlled behind the drum kit. Easing up on the throttle throws a brighter spotlight on the duo’s maturing songwriting, and clarifies just how lovely their voices are when tangled together.

“Blue and Gold Print” is a prime example. It begins with a slightly sad piano line courtesy of Ms. Gardner, whose voice is joined by Mr. Hammel on the first verse. Her voice is crisp and sharp; his is soft and wispy. That tension has always been there, but the quieter settings on “Re-Arrange Us” add a new layer of vulnerability to the music. When they both raise their voices as Mr. Hammel’s drums enter on the bridge, it’s enough to raise the hairs on the back of your neck.

This pair’s maturation feels less like a mellowing than a new confidence in songcraft and vocals. “Re-arrange Us” is by far the band’s most accessible album to date, but it navigates the pop terrain without sacrificing the band’s idiosyncratic personality and identity. “Get Better” opens the album with a swell of strings and drums backing Ms. Gardner’s falsetto, with the first verse being little more than a wispy mesh of piano dancing atop the driving pulse. The chorus is intoxicatingly harmonized — “everything’s gonna get lighter / even if it never gets better” — a bewildering contradiction that manages to feel like cathartic joy. Somehow, Mates of State pull off minor operatic moments such as these across the album’s 10 tracks.

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Islands aims for a different kind of pop grandiosity on “Arm’s Way.” The Montreal-based group emerged from the demise of the Unicorns, a ramshackle band that repurposed indie-pop clichés into euphorically goofy music. Islands proved itself to be less self-conscious on its omnivorous 2006 debut, “Return to the Sea.” “Arm’s Way” is equally ambitious, aiming for that last great decade of pop opulence: the 1970s. The album isn’t quite prog rock, nor is it bombastic and silly, à la Electric Light Orchestra. It’s more as if Elton John and his famed songwriting partner, Bernie Taupin, decided to make a “world music” album in 2008, when almost any culture’s indicative sound is only a download away.

But “Arm’s Way” doesn’t simply meander through sounds and ideas. “J’aime Vous Voire Quitter” starts off as a punk-guitar Balkan folk song and ends in an almost West African carnival of percussion and vocal “whoops.” “Abominable Snow” rises out of strummed guitar lines that split the difference between country and mariachi, then hits a full-tilt pace where bursts of strings sound like a murder of crows taking flight, and finally ends in a gentle voice-and-guitar duet that’s pure doo-wop. “Life in Jail” sounds like the crooning ballad a juvenile delinquent would sing in a 1950s B picture. And “Pieces of You” is equal parts 1920s cabaret and 1990s indie pop.

What’s amazing is how Islands seamlessly threads all these ideas together without sounding mannered or like clunky pastiche. The duo’s singer-songwriter, Nick Thorburn, is touched by a bit of Todd Rundgren syndrome, that gift-curse of never hearing a musical sound that he didn’t want to use in his own songs. Mr. Thorburn, though, isn’t as insistent just yet, and prefers to make music that feels organic. Indeed, the most disarming elements of “Arm’s Way” are its beguiling pacing and engaging arrangements. That Mr. Thorburn explores rather dark, lyrical territory over these plush arrangements — witness the “creeper in my home, crawling through the window / I grabbed the kitchen knife, couldn’t stick it in though,” in “Creeper” — adds another impressive wrinkle to the album’s rich layers. “Arm’s Way” is not an album for everyone, but that’s just the point: Pop need not always be popular.