“El Sistema” was created 40 years ago in Venezuela to help foster social change by building youth orchestras among disadvantaged children. It has grown into a musical movement, counting among its graduates Gustavo Dudamel, the charismatic Music Director of the Los Angeles Philharmonic. Crescendo! The Power of Music follows students in two “Sistema”-inspired youth orchestra programs: “Play On, Philly!” in West Philadelphia; and the Harmony Program in Harlem, New York City. The film’s young musicians struggle against significant emotional and cultural roadblocks, sometimes set up by their own families. We meet Raven, a natural violinist whose rambunctiousness gets her in trouble (“Fortissimo, y’all!”); Zebadiah, an introspective boy who makes friends via the viola; and Mohammed, whose father insists he quit the trombone if he keeps failing classes. Music educators Stanford Thompson and Anne Fitzgibbon are heroes in these kids’ lives, helping them and countless others unlock their potential through the inspirational power of classical music.