BEFORE tonight's Philadelphia Orchestra concert, 30 lucky students from Play On, Philly! will perform on the Kimmel Center stage in the experience of a lifetime.

These members of St. Francis de Sales Firebird String Orchestra will play the first movement of Mozart's familiar "Eine Kleine Nachtmusik" ("A Little Night Music"), under the direction of Philadelphia Orchestra maestro Yannick Nezet-Seguin.

Founded at West Philadelphia's St. Francis de Sales School, Play On, Philly! is the local embodiment of Venezuela's visionary El Sistema. This now-international concept has helped thousands of children improve self-esteem and personal skills while learning music at a high level. Grades have to be maintained to continue in the program, so it has led to greater academic levels as well.

Play On, Philly! musicians have performed twice with our orchestra under the inspiring Simon Rattle, but this is their first opportunity to be led by Yannick.

Nezet-Seguin has already demonstrated a willingness to partner with young musicians throughout the area, involving other student orchestras and other programs outside the Kimmel Center.

"We are committed to working with young musicians such as those in Play On, Philly!," Nezet-Seguin said. "Our love and passion for music, for great music, is contagious. I personally want to encourage their hard work and talent and inspire them to persevere, enjoy making music and live their dream."

Play On, Philly! was cofounded in 2011 by Curtis graduate Stanford Thompson and philanthropist Carole Haas Gravagno, who has a boundless passion for bringing music to children whose schools have eliminated the arts.

Starting with 110 students at St. Francis de Sales School, Play On soon added more students from Friere Charter Middle School, in Center City. More than 200 students ages kindergarten to 13 now receive a tuition-free chance to play an instrument. They also get instruction in choir, general music, composition, chamber music and orchestra from professional teaching artists during daily three-hour practice sessions.

"I rehearsed with Rattle at Curtis, but never personally performed with him, and there are not many students who have," Thompson said. "The pride and energy we received from parents, school and colleagues after those two performances [with Rattle] was a shock, and many people wanted their children enrolled in the program.

"Those were the first times that a group of schoolchildren has opened such a concert, and it has served as a model for other orchestras around the country. Sometimes we take 60 kids to play, but they have inspired thousands, connected to the community and maybe affected social change. Because of this visibility, we've had invitations from the Mann, Orchestra 2001 and other organizations to partner with them."

Play On, Philly!'s vision is limited only by the funding for teachers, many of whom donate their time. The program's success is a logical argument for its continued growth, especially as it fills a huge arts gap for local public schools.

One visible model of success from the Venezuelan program is Gustavo Dudamel, who came from humble origins to become the head of that country's Simon Bolivar Orchestra, and who now conducts the Los Angeles Philharmonic.

Thompson could be a playing or freelancing musician, but his dedication to the community sends a powerful message. "You don't have to become a professional musician to benefit from this program," he said. "It's about pride, working together and becoming inspired.

"The concerts are important, too, for our teaching artists. They know that Simon and Yannick are donating their services - we couldn't afford them. Their dedication to music reinforces the value of all the time and effort our teachers put into this program."

After the Play On, Philly! performance tonight, Nezet-Seguin will lead the Philadelphia Orchestra in Mozart's Symphony No. 40 and the Piano Concerto No. 20, with the Canadian-born Jan Lisiecki, a remarkable artist at just 19, as soloist.

At 2 p.m. today, the program will consist of the 39th Symphony and the Piano Concerto No. 22, and tomorrow evening's concert will wrap the Mozart celebration with the magnificent final Symphony No. 41, the "Jupiter," and the marathon keyboard prowess of Lisiecki in the Piano Concerto No. 21.

Verizon Hall, Kimmel Center, Broad and Spruce streets, 2 and 8 p.m. today and 8 p.m. tomorrow. Sold out at press time but more tickets may become available. 215-893-1999, kimmelcenter.org.