Ms. Josefowicz came to national attention in 1994 when she made her Carnegie Hall debut with Sir Neville Marriner and the Academy of St. Martin in the Fields and has since appeared with many of the world's most prestigious orchestras and eminent conductors.  A regular, close collaborator of leading composers of the day such as John Adams and Oliver Knussen, she is a strong advocate of new music - a characteristic which is reflected in her diverse programs and her enthusiasm for premiering new works.  During the 08/09 season Ms. Josefowicz premiered concertos written for her by Esa-Pekka Salonen/Los Angeles Philharmonic and Steve Mackey/St. Louis Symphony and played first performances of Thomas Adès’ violin concerto Concentric Paths with the Philadelphia Orchestra and San Francisco and Seattle symphonies. In October 2009 she premieres another concerto written for her by Colin Matthews with the City of Birmingham Symphony Orchestra. In recognition of her passionate advocacy and genuine commitment to the music of today, Ms. Josefowicz was awarded a 2008 MacArthur Foundation Fellowship.

Recent appearances in North America include performances with the New York Philharmonic, the Minnesota Orchestra and St. Paul Chamber Orchestra and the Chicago, Pittsburgh, Detroit, Baltimore, Dallas, Houston and Cincinnati symphonies; a performance of John Adams' Violin Concerto in Carnegie Hall with the American Composers Orchestra under the baton of Mr. Adams; and recitals in San Francisco, Baltimore, Los Angeles, Philadelphia and at Zankel Hall at Carnegie Hall.