They were an eccentric group with eclectic tastes, gathering on weekends or weeknights to sing Renaissance songs or dance the way dancing was done in 18th-century England.

These were small, private affairs held among artists in Bluemont, where they all chanced to meet as neighbors during the mid-1970s.

Eventually, word of the somewhat odd, exclusive soirees traveled beyond the regulars, and people began to ask, "When's the next dance?" Or, "I play the guitar, might I join in?" The answer was always yes, and the eventual result was what is known today as the Bluemont Concert Series, a regional arts force that presents intimate, old-fashioned musical and theatrical fun for all ages.

Harkening back to an era of family picnics enlivened by a fiddler's tunes, Bluemont offers in-your-neighborhood alternatives to concert halls and numbered seats. Since 1976, Bluemont has presented 3,488 events in 80 communities for an estimated audience of more than 2 million, with 15,602 artists participating.

But Bluemont's success has created a problem of its own.

Now the question is: As it expands, how does a small organization hang on to the intimacy it treasures above all else?

"It doesn't happen easily," said Peter Dunning, Bluemont's founder, president and artistic director, at its headquarters in Leesburg. "How do you retain a formula of high-quality, affordable, community-based activity and retain the potential for sharing, for give-and-take between the audience and performers, while growing larger all the time?"

Dunning, one of the sole remaining members from Bluemont's infant years, cringes at the thought of a bureaucracy running the concert series or of consolidating the ever-increasing number of lawn concerts into one show at a cavernous theater. That would be the easy, efficient thing to do.

"We could hire Willie Nelson in a hall, but does that fit the purpose of what we want to do? No," Dunning said, in one breath dismissing the idea as ludicrous.

The series, which focuses on traditional and folk music, was Dunning's one-man production for years. Only last year, more than two decades after its inception, was another executive, Bonnie Mattingly, hired as managing director.

Mattingly, who lives in Upperville, was external affairs manager for the Metropolitan Washington Airports Authority when she decided to shuck the commuter world and work closer to home. "The idea was to shift some of the administrative responsibility away from Peter so he could focus more on the artistic side," said Mattingly, a former flight instructor. "For me it's a shift from aviation to the arts, but they're both sectors of life that I find interesting and fun."

The support staff has grown to five and handles the bookkeeping, scheduling and fund-raising with the help of hundreds of volunteers.

"We're at a whole new level of administration and organization. . . . We've needed Bonnie for a long time," Dunning said. "We've got the work for a little bureaucracy, but we try to handle that through volunteers and the resources available to us."

The phones are ever ringing in the four-room Bluemont office at the corner of King and Market streets in Leesburg. It's still a family affair for Dunning, who met his wife, Melissa, a concert singer, through the series; she keeps the books. His daughters Lily, 14, and Hannah, 11, volunteer, and Rupert, the dog, is a roving stress reliever for the small staff.

What had the staff busy last week was a lesser-known component of the nonprofit Bluemont Concert Series: the Artists-in-Education program, which organizers consider to be Bluemont's largest and most important role in the community.

The Bluemont Concert Series sponsored 187 in-school performances as curriculum enrichment last year, compared with 71 community concerts. Dunning considers that outreach crucial, akin to "creating a constituency" for the concerts as the students grow up, he said.

Judy Schneider, Artist-in-Education coordinator, offers schools across Northern Virginia a detailed directory of musical and theatrical groups that Bluemont will sponsor at no cost to the schools.

"We feel it's the program that most speaks to our objectives," Schneider said.

And if the schools don't see what they're looking for in the directory, Schneider and Dunning will find it.

"A school in Middleburg called asking for something Russian because they were studying Russia, and we didn't have anyone locally," Schneider said. "So I asked Peter, and of course he found someone."

The Sunday summer concerts are Bluemont's public side, but even they come with an unpublicized bonus: Every band that plays one of the weekend concerts, which are held in 19 Virginia jurisdictions, is required by contract to perform in a local nursing home or hospital, as well. That, Mattingly said, is "a much-hidden service."

She said some of the best performances seem to happen during those tiny concerts, where both the audience and performers often leave changed.

The organizers are determined to keep the cost of attending the performances as low as they can. Dunning, 54, said he"reluctantly" added a $3 admission fee during the 1980s as it became difficult to payperformers from donations alone. Bluemont's budget last year was $650,000, gathered from local government support, donations, partnerships with the private sector and admission fees.

"My work with Bluemont is an extension of my strong belief in the importance of the physical environment," said Dunning, who grew up in Connecticut and settled in Loudoun County after walking the Appalachian Trail during the early 1970s.

He had found a job in Harpers Ferry, W.Va., writing stories about his adventure when he met his musically inclined neighbors in Bluemont. He said he never dreamed he would become a professional concert organizer as a result of those friendships, but he loved sharing music and didn't want to see the neighborly tradition fade away.

"The cultural environment has the potential to be a nutrient in our lives, and like the physical environment, it's frail and needs nurturing," he said. "We think our project had its own value -- true, direct merit." CAPTION: With the Bluemont Concert Series' appeal growing, Bonnie Mattingly, foreground, was brought in to help founder Peter Dunning. ec CAPTION: The Ululating Mummies, a Richmond band set to perform at 7 p.m. tonight at the Loudoun County Courthouse, are representative of Bluemont's eclectic offerings. ec