When Big Bad World hit stores in 2008, Plain White T’s were still reeling from the unexpected success of “Hey There Delilah.” To avoid being pigeonholed, they wound up steering clear of everything that made “Delilah” a hit, doing away with acoustic ballads and emphasizing loud, zippy pop songs instead.

Released two years later, The Wonders of the Younger doesn’t have such a noticeable chip on its shoulder.

Plain White T’s sound more comfortable this time around, never relying exclusively on the midtempo songwriting that made them famous but hardly shying away from it, either.

They’ve learned to be more adventurous, too, shifting frontman duties on the album’s best song -- “Rhythm of Love,” an acoustic, beach-worthy pop tune with lead vocals by guitarist Tim Lopez -- and decorating the rest of the track list with strings (“Last Breath”), electronics (“Map of the World”), cabaret-style vocal harmonies (“Welcome to Mystery”), and bouncing piano (“Boomerang”).

Holding the whole thing together is Tom Higgenson’s love for a good melody; he makes every line sound like a chorus, and The Wonders of the Younger is almost aggressively tuneful as a result, with enough quirks thrown into the mix to keep things from getting too sugary.

As far as pop albums go, this one strikes a rare balance between familiarity and novelty.