When Del McCoury was a boy in rural North Carolina and south-central Pennsylvania, the biggest thing in country music was a new configuration that was turning heads across the nation. Designed to be on the cutting edge of commercial viability, the new lineup brought the banjo and mandolin to the front of the mix and broke into whirlwind breakdowns. Curiously, the new style was named for the band that invented it.

Patti Longmire The Del McCoury band's new CD, "The Company We Keep," is its most traditional offering in decades. Del McCoury Where: Carnegie Lecture Hall, Oakland When: 8 p.m. Saturday Tickets: $45 door, $40 advance, $20 student rush, 412-394-3353

It was the answer to a boy's wildest dreams when, in 1963, McCoury was invited to apprentice at the side of Bill Monroe, the mando picker who led The Blue Grass Boys in the birth of bluegrass. His stint as rhythm guitarist and lead singer was short, but it launched his career.

Some 40 years later, McCoury is one of the leading figures in the music he grew to love. By his own admission, he got to where he is by breaking all the rules.

When McCoury visits Carnegie Lecture Hall on Saturday, as part of a concert series sponsored by Calliope: The Pittsburgh Folk Music Society, he won't be bringing a set list. All of his shows, he says, are at the audiences' request. McCoury, his sons Ronnie McCoury and Rob McCoury, and Jason Carter and Mike Bub are prepared to draw from the elder's unusually diverse backlog of songs.

While Monroe explored several configurations, he's mostly remembered for a distinctive (some say rigid) musical style. Bluegrass traditionalists like it best when the music stays that way.

"I always knew, when I first started, that I'd have to have my own songs," says McCoury, wheezing through the tail end of a winter cold earlier this week. "I started out playing some traditional songs. But when it came to choosing songs, I guess everybody has their own tastes, and I saw there were so many great songs outside the bluegrass field. That's why I recorded the things I did. A good song is a good song."

Purists balked. How dare a former Monroe sideman muddy the waters by taking the music where it hadn't been before?

"Yeah," he says, laughing. "I got some of that, but it wasn't a lot. One guy I played with, he said, 'Bluegrass is supposed to be three chords, maybe four. You're doing songs with five chords or more in there.' I just laughed. I've always just played songs that I liked."

Now, some critics are taking the opposite tack. McCoury's new CD, "The Company We Keep," is more traditional in form than anything he's done in decades. How dare a progressive bluegrass picker follow the music back to its roots?

"You know, you hear all kinds of things," he says. "I guess the truth is, I just like variety. We didn't start out to make a traditional album. It just came out that way."

Part of the explanation might be the origin of some of the songs. For the first time in his career, McCoury co-wrote several songs with other writers. Several of the co-written tunes didn't make the cut, but two of the tunes were written by McCoury and mainstream country hit songwriter Harley Allen. One is by McCoury and four-time ASCAP Country Songwriter of the Year Don Schlitz.

"I went in without any ideas," he says. "Just completely blank. Harley said he had this idea about telling a musician to never grow up ['Never Grow Up Boy']. And Don, like other songwriters, likes to get his songs out on the road, so we wrote this song about, if here's where you are then it's where you're supposed to be [If Here is Where You Are']."

McCoury is a busy guy. After Saturday's performance, he has three weeks to crank out his first gospel album. Early next year he's scheduled to work on a DVD, and he plans to record a live album by the end of the year.