The mandolin is an instrument to which most people pay little attention, even though it pops up regularly in country music, classic rock, jazz and bluegrass. But if you're a die-hard fan of this descendant of the lute (which, much like a guitar, can be both plucked and strummed, although it's smaller and has a higher pitch) this Saturday will be your nirvana, when as many as 40 musicians will combine into the area's only large mandolin orchestra for its fifth anniversary concert.

Although such a gathering might seem to happen once in a blue moon, it was commonplace only a few decades ago. According to Pittsburgh Mandolin Orchestra director Charley Rappaport, such ensembles were a popular American fad from the late 19th century up to the early 1930s, and Pittsburgh was no exception.

"There were some famous teachers and a lot of players from here," Rappaport explains. "Valentine Abt was a world-renowned soloist and composer from the turn of the century. And H. Russell Truitt was a teacher here for 65 years -- almost every week I meet some older person who studied with him."

Today, however, there are only about 40 mandolin orchestras in the United States, but the instrument is growing in popularity, as popular bands from Nickel Creek to the White Stripes feature it on their albums.

Pittsburgh's orchestra originated in September 2002, when Alan Epstein came back enthused from a mandolin convention, where he witnessed a group of 150 players. "Alan got his friends together in his living room. There are some great mandolin players in Pittsburgh, though most are devoted to other forms of folk music."

After three years, Epstein moved to Michigan, passing the baton to Don Maue, a Duquesne University instructor in studio engineering who is also one of the founders of the classical Guitar Society of Fine Art. With Maue's schedule becoming too hectic, Rappaport, a third-generation mandolin player (hearkening back to his mother and grandfather from Odessa) took over the post last year. He brought his experience since the early '70s playing around the country with his group The Great American Gypsies, most recently in Atlanta. "We were the house band at the Peachtree Hotel, playing every night, six nights a week for 26 years."

Rappaport likens the highly specialized arrangements of the Mandolin Orchestra to that of a symphonic pop orchestra such as the Boston Pops.

"It's very light and entertaining. We do a lot of Celtic stuff -- an Irish tune, a Welsh rhapsody, and an old Scottish folksong from the Skene Manuscript, which is one of the earliest written documents of folk music. But then we're also doing "Chattanooga Choo Choo" and a piece by Schubert, so it's all over the map."

Founder Epstein will return to play two solo works with accompaniment, one a jazz piece by Michigan composer Don Julin. And his backing truly is "orchestral" -- the group includes mandolas (an equivalent to the viola), mandocellos, and mandobasses, along with upright string bass. "We also have a section of guitarists who add the foundation and the chords, and a different tone quality to the overall sound," Rappaport explains.

A resident of Erie, Rappaport travels down Route 79 three days a week to teach about 30 students at Steve Miklas' Acoustic Music Works in Squirrel Hill, the region's unofficial mandolin mecca. In addition to playing Italian weddings and spending weekends as a strolling musician at Chovy's Restaurant in Meadville, Rappaport shepherds a smaller group called the Three Rivers Mandolin Consort.

"We wanted to play more challenging music than was available in the orchestral setting. So we do ethnic music from countries where the mandolin is popular -- Italy, Spain, Poland, Greece, Russia -- and then we play classic and early baroque music, as well as pieces that were written for mandolin groups in the 20th century. We play in venues that are too small for the orchestra -- in fact, we have a show at the Carnegie Library on Nov. 11."

Audience members on Saturday might be most surprised by the group's wide demographic when they behold four generations onstage. "Our youngest player is 12, and our oldest is 88," adds Rappaport. "We have an ensemble of young people -- three boys and two girls. They've all played for years on other instruments -- violin, cello -- and picked up the mandolin because they enjoy it. They play so great that you wouldn't believe they were kids if you turned your back."

Such youthful participation bodes well for the future of the mandolin, and local folk enthusiasts should also count their blessings, Rappaport emphasizes. "You can live in most cities and never see a mandolin orchestra, but the one we've got is really thriving. Every place we play, the reception is exceptional, and the audiences are just fantastic. So we're really lucky here."