In 1986, four years after the death of Thelonious Monk, a benefit concert honoring the memory of the enigmatic jazz composer and pianist was held at Washington’s Constitution Hall. There was talk at the time of building a statue in Rocky Mount, N.C., Monk’s home town, but his widow, Nellie, hoped for a more dynamic way of remembering her husband.

“She wanted something that was living, vibrant and involved young people,” recalls Thomas R. Carter, who organized that concert 25 years ago.

Out of a widow’s wish grew the Thelonious Monk Institute of Jazz, which has become one of the most important behind-the-scenes forces in promoting the music that Monk helped define. The Washington-based institute is best known for its annual international competition, which has launched the careers of such jazz stars as Joshua Redman, Jane Monheit and Eric Lewis, and is by far the most significant musical contest in the jazz world.

“It was a huge moment in my life as a jazz musician,” says Redman, who won the 1991 saxophone competition. “I was out of college only a few months. At the time, I had every intention of going to law school the next year.”

Redman was taking a year off to explore his interest in jazz and entered the competition “as a lark,” competing against such stellar saxophonists as Eric Alexander, Chris Potter and Tim Warfield.

“I often feel a little sheepish about it,” Redman says. “I had a great time, but I honestly feel I shouldn’t have won.”

Ready for the spotlight or not, Redman became an instant star in the jazz world, and the Monk competition has come to be recognized as the nation’s top forum for discovering new jazz talent.

Redman will be among two dozen past competitors returning to Washington this weekend as the Monk Institute celebrates its 25th anniversary. Twelve young pianists from around the world will take part in this year’s competition, which begins Sunday at 1 p.m. at the National Museum of Natural History’s Baird Auditorium. Three finalists will perform Monday night at the Kennedy Center’s Eisenhower Theater, where the winner will be chosen.

The competition, which is modeled after the Van Cliburn and Tchaikovsky contests in classical music, guarantees its winners a recording contract, concert bookings and scholarship money.

“It’s one of the best things happening in jazz for younger musicians,” says Monheit, whose second-place finish in 1998 helped propel her international career. “I don’t know where I’d be without it.”

In recent years, the Monk competition has emerged as something more than a listening party for jazz buffs. It has also become one of Washington’s most glittering celebrity spectacles, bringing together luminaries from jazz, entertainment and diplomacy. The co-chairs of this year’s gala are Quincy Jones, Madeleine Albright, Colin Powell and Debra Lee, the chief executive of BET. A special honor will be given to singer Aretha Franklin on Monday.

“What started as an idea to honor Thelonious Monk has grown into a major institution,” says Carter, who has been president of the Monk Institute since its inception. “There’s no more fitting place for jazz, America’s music, to play a major role than here in Washington.”

But after the spotlights are turned out and the A-list guests have gone home, there remains the hard day-to-day work of keeping an art form alive. From the beginning, for Carter, Nellie Monk (who died in 2002) and T.S. Monk — Thelonious Monk Jr., the chairman of the institute’s board of trustees — education was at the core of the institute’s mission.

Through a multidisciplinary curriculum, Carter says the institute teaches more than a million public school students a year about the development of jazz and blues music. The group works with performing-arts high schools and has mentoring programs throughout the country. All of its educational programs are free.

“It’s amazing how this really does change lives,” Carter says.

Ben Williams, who grew up in Northeast Washington, was 11 when he began playing the bass at Hardy Middle School. When he was barely half as tall as his towering instrument, he attended Monk Institute programs at the Fillmore Arts Center in the District, getting one-on-one lessons from Ron Carter, a renowned bass player who spent years with Miles Davis.

Williams, now 26, went on to graduate from the Duke Ellington School of the Arts and Michigan State University and to receive a master’s degree from the Juilliard School in New York. Two years after taking the top prize in the Monk Institute’s bass competition, he leads his own group, has released a debut recording, “State of Art,” and plays in various ensembles, including a trio led by another past winner of the Monk competition, pianist Jacky Terrasson. (The trio will appear Oct. 21-22 at Bohemian Caverns.)

“I saw this open door that was there when I won,” Williams says. “It’s done wonders, to say the least.”

For two years, singer Gretchen Parlato studied with jazz masters and toured the world as part of the Monk Institute’s intensive college-level program, based in Los Angeles. Parlato was the first singer and only the second woman chosen for the all-expenses-paid program.

“It’s a life-changing thing and a unique experience,” says Parlato. “You end up tapping into yourself and doing a lot of soul-searching.”

After her two-year apprenticeship, Parlato has blossomed into one of the most sought-after singers in jazz. Last month, she won DownBeat magazine’s critics’ poll as the top “rising star” among female singers. She has released three CDs and performed to rave reviews all over the world in the seven years since she won the vocal competition in 2004.

“When I participated in the competition and happened to win,” she says, “people leaned in and listened a little bit closer to what I was doing.”

Twenty years after his surprise victory, Redman remains perhaps the biggest jazz star to emerge from the Monk competition. Once he began performing on the jazz circuit, he gave up his slot at Yale Law School and has never looked back.

“I never liked the idea of competition in music, especially in jazz, which is based on your own personal sound and what you have to say at that moment,” he says. “But people get excited about competitions, and any opportunities for wider exposure for the music and the art form, I welcome wholeheartedly. It’s a great thing.”