"Bluegrass is changing into more of a family-oriented entertainment rather than nightclub entertainment," says Sid Rosenberg, a member of the Capital Area Bluegrass and Old Time Music Association (CABOMA). Proof of that is last year's inaugural Glen Echo Bluegrass and Old Time Music Festival, which drew more than 8,500 people. "You can go out and play bluegrass in the park," says Rosenberg. "You don't even need to drag an amplifier out there."

Tonightat 8, however, the bluegrass scene will move indoors at the Birchmere, where CABOMA will host a concert to benefit the upcoming second annual free festival.

Performers scheduled to appear include the Busby Brothers, fronted by Buzz Busby, who, says Rosenberg, "has been called the father of Washington bluegrass." Also on the bill is GrazzMatazz, a Washington band whose album "Delinquent Minor" won a Wammy from the Washington Area Music Association in 1985 for best acoustic album. Rounding out the evening will be the Grass Reflection, the Last Straw and Red Toad Road.

"Around here it's always been a hobby activity for hundreds of people," explains Rosenberg, who plays in a bluegrass band himself (the Sprouts of Grass). "Just like people who play poker, bluegrass players get together and jam all afternoon."