Ever since signing with Sugar Hill in 1999, Dolly Parton has been on a hot streak, putting out a steady stream of rootsy albums that found her creatively re-energized.

It all started with the all-bluegrass Grass Is Blue, which won a Grammy in 2000, and she worked a similar territory on the subsequent Little Sparrow (2001) and started to branch out a bit with Halos & Horns (2002), which remained in the acoustic realm but wasn't as strictly bluegrass.

Now, with Those Were the Days, she breaks free of bluegrass in the strictest sense by recording an album of her favorite songs from the '60s and '70s.

While this isn't traditional bluegrass by any means, it's still rootsy acoustic music, due to both the instrumentation and choice of songs, which are, with the exceptions of Tommy James' "Crimson and Clover" and John Lennon's "Imagine," firmly within the folk and folk-rock tradition of the '60s.

Parton has also styled Those Were the Days as a duet album, inviting the original singers or songwriters when they were available, and bringing in newer singers when they were not (like Nickel Creek providing harmonies on Bob Dylan's "Blowin' in the Wind," Norah Jones and Lee Ann Womack for "Where Have All the Flowers Gone," and Keith Urban for "Twelfth of Never").

The arrangements are at once tasteful, imaginative, and relatively unsurprising -- there are no left hooks, no electric sitars, or wah-wah guitars (although there is the trademark electric guitar tremolo on "Crimson and Clover"), just vivid, successful, slight reworkings of familiar songs that make them sound fresh again.

Since Parton has been making strong acoustic records for six years now, this doesn't have the same impact as Grass Is Blue, but that doesn't mean that Those Were the Days is a bad record.

Far from it, actually -- it's yet another very good album, one with no weak spots, from a revitalized Dolly Parton, who has turned into one of the more reliable country music veterans of the 2000s.