It has expanded beyond the how-to-play format with sales of CDs, DVDs and an increasing online presence. Its catalog of music books is 3,000 deep, and the company recently opened an office in London to expand marketing efforts in Europe.

In the 1940s, fresh out of World War II, Mel Bay was teaching guitar in St. Louis County when he developed his own method and put it into writing with "Mel Bay's Orchestral Chord System for Guitar," intended to teach guitarists more powerful-sounding chords for use in big bands and show orchestras. He went to New York's three largest music publishers.

Bay decided to self-publish. He made a go of it by taking the train to other cities and meeting face-to-face with guitar teachers, pitching his method. Then along came the King.

Elvis Presley burst onto the popular music scene in the 1950s, ushering in rock 'n' roll. Suddenly the guitar, previously considered by the music elite as little more than a rhythm instrument, was all the rage. Thanks to his personal contacts, guitar teachers around the country were turning to Bay as students by the thousands took up the instrument.

The Beatles arrived in the early 1960s, bringing along another wave of popularity for the guitar that wavered only once — in the early 1980s when small, portable keyboards briefly were the rage. The company's biggest seller, a book for beginners called "Modern Guitar Method Grade 1," has sold 8 million copies since it came out in 1949. It has been revised four times. Frank Vignola, whose recordings have ranged from jazz to bluegrass said he learned guitar starting at age 6 using the Mel Bay method.

The how-to books have changed over the years. Once strictly written instruction, many now include CDs that allow the students to hear how the tune is supposed to sound and play along with it.

Mel Bay died in 1997 at age 86. William, now 62, runs the company along with his son, Bryndon, 33. Another son, Collin, is studying jazz guitar at New School University in New York. Mel Bay Publications has expanded well beyond the guitar. Its books teach dozens of instruments and styles. There are books for the clarinet, the banjo, the sax, but also for the pan flute, dulcimer and darbuka, a Middle Eastern drum. You can use a Mel Bay book to play jazz or rock, but also bluegrass or Celtic music.

In recent years, Mel Bay expanded into recordings. Its "MB3" featuring jazz guitarists Vic Juris, Corey Christiansen and Jimmy Bruno was No. 1 on the Jazz Week album chart earlier this year. It also offers DVDs featuring concerts, anthologies, jam sessions.

The Internet has also changed the way the company operates. William Bay estimates that about one-third of sales are via the Web through Amazon.com and other sites. Increasingly, sheet music can be purchased and downloaded from the company's Web site, http://www.melbay.com.

Most workers juggle a variety of tasks. That goes for William Bay himself. On many days, he'll go into the studio with one of his guitars, performing the etudes and lessons he often writes for CDs that students play along with as they learn the instrument.

That love of playing remains evident inside the company. William keeps a guitar next to his desk and often stops to play. He recalled a company Christmas party where so many of the worker/musicians took turns the party kept going long into the night.