Lewis Cornwell is an experienced theory teacher and composer with research interests in the area of 20th century Japanese composers. A graduate of the University of Sydney, he studied composition in the Department of Music with Peter Sculthorpe. He began tutoring in harmony in 1982, both in the Music Department and at the Sydney Conservatorium of Music, gaining a full-time position at the Conservatorium in 1989, where he served as chair of musicology from 2002-2004 and 2006-2010, and associate dean (ICT/eLearning) from 2004-2006.

Lewis was a founding member of the composers' collective Music Performed and served a term as its administrator, helping to organise workshops of New Music for young composers. His works have been included in concerts given by the ISCM, the Mused Ensemble and the Seymour Group.

His interest in studying and composing new music for traditional Japanese instruments has led to performances of his works in Japan and Europe. In January 1997, Interweave, for shô and guitar, received its first performance at the 18th Festival and Conference of the Asian Composers' League in Manila. Lewis was a co-organiser of the Takemitsu Symposium and Tribute Concert, which was held at the University of Sydney in 1998.

As an oboist, he plays in local orchestras and chamber ensembles and assists with their administration.

Lewis believes training in theory and analysis gives students the ability to make their own discoveries about their music. He likes to work on the interface between craft and creativity, and has said that, “to know the conventions is to begin to understand the music that so marvellously transcends them”.