Composer James Hopkins has written works for practically every instrument and ensemble. "Highly idiomatic writing" and "colorful, exotic orchestrations" are often cited as characteristics of his work. His output ranges in scale from intimate solo and choral pieces to large orchestral works, some with chorus. His catalog includes seven symphonies and four concertos.

Among performers and ensembles who have played his works are the National Symphony, the Seattle Symphony and Symphony Chorus, organists David Higgs, Fredrick Swann and Diane Meredith Belcher, the North Shore Band, the Fine Arts Quartet and the Pacific Symphony and Pacific Chorale.

Organizations that have commissioned his works include the National Endowment for the Arts, the Orange County Philharmonic Society, the Orquesta Ciudad de Granada (Spain), and the Pasadena Chamber Orchestra, as well as numerous churches and educational institutions.

His most recent major composition, Concierto de Los Angeles, was commissioned by the American Guild of Organists for its 2004 National Convention. Premiered by the Los Angeles Philharmonic Orchestra and soloist Cherry Rhodes, it was the first work for organ to be performed in a public concert at the Walt Disney Concert Hall.