Like many New Yorkers, Allegra Klein, a violinist and arts administrator, wanted to do something to help after the terrorist attacks five years ago. Through her contacts as coordinator of the Vermont-based Marlboro Music Festival, she was able to persuade members of the Shanghai, Juilliard, and Guarneri String Quartets, along with other top musicians, to perform without pay in a commemorative benefit concert to be held the following year.

“I thought there would be a strong need for something on the first anniversary of 9/11,” Ms. Klein, who is now the director of operations at the New York Youth Symphony, said. “We wanted something carefully thought out and of high quality that would make a statement and raise money for charity.”

Ms. Klein’s efforts grew into Musicians for Harmony, a group formed to promote cultural understanding through music. The organization, whose players donate their services, will hold its fifth annual “Concert for Peace” tonight at Merkin Concert Hall. The event will be broadcast live on WNYC Radio (93.9 FM) at 7:30 p.m.

Four years ago, Ms. Klein turned to Patrick Derivaz, a musician-composer, producer, and engineer, to bring world music and other styles to the group’s first event. In response, Mr. Derivaz, now the artistic director of Musicians for Harmony, formed the chamber ensemble Musique Sans Frontieres (Music Without Borders), arranging to bring a Lebanese oud player and an Israeli percussionist to perform with the ensemble at the first commemorative concert.

Musicians for Harmony’s concerts in recent years have featured an Egyptian tenor singing in Hebrew and Arabic; an Iraqi pianist; a ney player from Iran, and a Greek bouzouki player. The group also collaborates with organizations like the World Music Institute to arrange paid engagements for musicians who have traveled from other countries to supplement the free concerts they give.

Since 2001,Ms. Klein said, the group’s mission has evolved from commemorating to “becoming an instrument of hope to the world by reaching out and saying, ‘What can we do about it? Let’s bring people together to prevent more tragedies from happening.'”

The classical side of Monday’s concert will feature the pianist Leon Fleisher and members of the Guarneri and Orion quartets playing Brahms and Mozart, while the violinist Mark O’Connor will perform the world premiere of his own composition, “Harmony,” a work for violin and string orchestra that was commissioned by Musicians for Harmony. The Knights, a group of young players, will accompany him. In a nod to American music, Tony Trischka, a banjo player, will play as a soloist with Musique Sans Frontieres, which will also perform Mr. Derivaz’s arrangement of a medley of Civil War songs.

In the future, the group hopes to expand to other cities, as well as to present more concerts by Musique Sans Frontieres. It is also launching an afterschool program for Brooklyn middle school students this fall. And Ms Klein remains optimistic in her belief in the healing power of music. “It does foster peace,” she said. “I truly believe that.”