Zwilich's compositional style is marked by an obsession with "the idea of generating an entire work – large-scale structure, melodic and harmonic language, and developmental processes – from its initial motives." In addition to large scale orchestral works like Symbolon (1988), Symphony No. 2 (Cello Symphony) (1985), and Symphony No. 3 (1992), she has written a number of notable, smaller-scale concertos. These include works for trombone (1988), bass trombone (1989), flute (1989), oboe (1990), bassoon (1992), horn (1993), trumpet (1994) and clarinet (2002). She has also written a small number of choral works and song cycles. Zwilich's music was conducted by Pierre Boulez at Juilliard in 1975. Her major breakthrough came after winning the 1983 Pulitzer Prize for her Symphony No. 1. Following this, she was commissioned to work on two more symphonies, for the San Francisco Symphony and for the New York Philharmonic's 150th anniversary. Symbolon has been performed in Europe, Asia and America.