The San Diego Young Artists Symphony provides orchestral and chamber music training for young musicians who have the ability and desire to study and perform symphonic repertoire, in an environment that has expectations and standards of excellence similar to those of a music conservatory.

SDYAS was established in February 1995 by the late maestro Louis Campiglia as a nonprofit organization with a mission to provide serious music students the opportunity to study, enjoy, and perform challenging symphonic literature. Assisted by a volunteer Board of Trustees, Campiglia's vision for YAS continues today under the music direction of maestra Mary Gerard, highly celebrated for her success as a gifted teacher of the violin and viola. In her career, she held first violin position with the San Diego Symphony, the San Diego Chamber Orchestra, the Starlight Theatre Orchestra, and the San Diego Opera Orchestra. Her career has included a professorship in the Music Department at San Diego State University.

The YAS has also served as the orchestra-in-residence at Mesa College. In addition to its full orchestra, the YAS sponsors three training orchestras: Con Brio and the Fiddle 'n' Bow ensemble (both conducted by noted violinist Hernan Constantino) and Winds 'n' Brass, conducted by John Borodach. These three programs instruct less-experienced players in the fundamentals of ensemble performance and emphasize the joy of music.

By 2013, the group had been renamed the Mainly Mozart Youth Orchestra.