"Mature" is one of those words that has potentially lethal consequences when it enters the realm of the rock-and-roll band. Urban pop (including soul and R&B but not hip-hop) and jazz and blues seem immune to this problem, but when maturity strikes a rock band, it too often leaves them sounding boring and perhaps over-serious. Then there’s the need to fill the void left when you take sex and drugs out of the rock-and-roll equation.

That in part is what has made the New York City–based trio Ivy, who headlined downstairs at the Middle East a week ago Wednesday, such a pleasure over the course of an eight-year career that has seen them bounced from the semi-independent Atlantic alternative imprint Seed to Atlantic proper, then to the Sony 550 label (which promptly re-released the band’s 1997 Atlantic CD Apartment Life), and now to the semi-independent Nettwerk label, which released the trio’s third full-length, Long Distance, a couple of months ago. From the very start, Ivy were a "difficult" band in the sense that they were playing music inspired by the swinging ’60s sounds of Burt Bacharach and the adults-only sensibility of French pop icon Serge Gainsbourg, but doing so without the irony or the jokiness that infected the lounge-pop/exotica revival of the mid ’90s. Ivy may have shared some influences with that loose movement, but they aren’t part of it. Instead, this trio — alluring French-born and -accented singer Dominique Durand, guitarist Andy Chase (her significant other; sorry, boys), and bassist Adam Schlesinger (who’s also one of the two principals in Fountains of Wayne) — have focused on creating adult pop for people who aren’t quite ready to make the transition to adulthood. In other words, late-twenty- and thirtysomethings who haven’t yet settled down emotionally, financially, socially, romantically, or otherwise. You could almost call it the Sex in the City demo if that show weren’t so weighted toward a female audience. Their music is full of smooth, vaguely jazzy guitar hooks, sultry vocals, bittersweet romance, retro horn arrangements, and lots and lots of "ba ba dop bop ba" lyrical refrains. Most important, they’ve continued to make music that, though miles from savage sex and drugs or raucous rock and roll, is both sexy and subtly unbridled.

Unfortunately, those elements didn’t come through as strongly as they might have at the Middle East. Indeed, there were times when it was hard not to feel that as a mature pop band even Ivy aren’t immune to the boring bug. Or maybe they were just having a down night. Either way, nothing they did erased the considerable charms of Long Distance.