On this, their fourth album, the Steep Canyon Rangers make one thing perfectly clear: if they stay together, nothing is likely to stop their rise to the top of the bluegrass world, to follow in the footsteps of Ralph Stanley and Del McCoury, the reigning champs and elder statesmen of pure bluegrass.

These five young men, who got together in Chapel Hill, North Carolina, in the 1990s, have it all: picking skills, vocals, harmonies and -- not least -- a batch of very fine original songs. Except for the 1920s jug-band standard "Don't Ease Me In," the Rangers fashioned the material on their own, exposing roots in honkytonk, gospel and old-time Southern folk as well as (of course) traditional bluegrass.

Unlike some flashy younger bands, the Rangers have little desire to incorporate pop, rock and jazz elements into the music that Bill Monroe invented in the 1940s, in a vividly imagined but flawlessly organic fusion of stringband and blues sounds as picked lightning fast. Though their sound is distinctive and instantly recognizable (especially in lead guitarist Woody Platt's striking tenor vocals and in the band's muscular dynamics), the Rangers are more interested in putting new accents into old sounds than in transforming bluegrass into an urban acoustic music whose rural origins are more footnote than main text. Not, obviously, that the latter has no legitimacy; it's just that it's no longer something you can properly call bluegrass. This is bluegrass.

The songs take up familiar themes -- rambling, coal mining, heartbreak, downhome humor, tales from the Bible, the musician's life -- and yet, almost miraculously, never let them lapse into worn cliche. Written by the Rangers' banjo player and frequent songwriter Graham Sharp with the legendary dobro player Tut Taylor, "Pickin' on Josh" is an immensely likable tribute to another revered dobro master, "Uncle Josh" Graves (1927-2006), a mainstay of Flatt & Scruggs's Foggy Mountain Boys for many years. "New Sleepy-Eyed John" picks up the further adventures of a comic character from American folk music. Though an independent, unrelated song, "Be Still, Moses" had to have been conceived after Sharp heard the Carter Family's "Little Moses."

The title song borrows the lilting melody of Monroe's "Ashland Breakdown," but so does Si Kahn's "Wild Rose of the Mountain," which "Lovin' Pretty Women" resembles not just musically but thematically. A reliable source -- the estimable mountain-music authority David Freeman (who, as it happens, contributes this album's liner notes but does not raise the issue therein) -- insists Monroe composed the tune, that it was not something snatched while floating out there in the public domain. Still, I'm sure Monroe, wherever he is, doesn't mind in the least that Kahn and the Rangers carry it on. It's a tune eminently worth, er, recycling.