He played the piano for performers at many New York City venues, such as Carnegie Hall, Town Hall, the Oak Room at the Algonquin, Rainbow & Stars, and the Carlyle. He was the musical arranger for many performers, including Liza Minnelli and Karen Akers.
For many years he was the arranger, accompanist and conductor for Patti LuPone, and with writer-director Scott Wittman created several shows for LuPone. He was the arranger and musical director for two Lupone shows on Broadway: Matters of the Heart (2000) and Patti LuPone on Broadway (1995).
Gallagher co-wrote scores for several musicals:
- Have I Got a Girl for You: The Frankenstein Musical (with Joel Greenhouse and Penny Rockwell, 1986)
- What Not, which won the 1990 Richard Rodgers Production Award
- Whoop-Dee-Doo! (1993), which was nominated for the 1993 Outer Critics Circle Award and won the Drama Desk Award for Best Musical Revue
- When Pigs Fly (1996), which was produced internationally after an extended run Off-Broadway, and won the 1996 Outer Critics Circle award for Best Musical Revue, and the Drama Desk Award for Best Off-Broadway musical
He also wrote the title song for the Charles Busch play You Should Be So Lucky. and wrote the music for two musicals for the theatre company TheatreWorks/USA: Gold Rush! (with David Armstrong and Mark Waldrop) and A Christmas Carol (with David Armstrong and Mark Waldrop).
He received the MAC Award, Musical Director of the year, in 2004.
- Jones, Kenneth. "Dick Gallagher, Award-Winning Off-Broadway Composer and Musical Director, Dead at 49" playbill.com, January 24, 2005
- Listing Internet Broadway Database, accessed August 16, 2013
- Holden, Stephen. "Stage: 'The Frankenstein Musical' " The New York Times, November 2, 1986
- Brantley, Ben. "Charles Busch Takes On a Trouser Role" The New York Times (reprinted at www.charlesbusch.com), accessed August 16, 2013
- Ehren, Christine. "Last Chance: 'Gold Rush!' at Theatreworks/USA Ends Aug. 7" playbill.com, August 5, 1999
- "'Gold Rush!' program" theatreworksusa.org, 2006, accessed August 2013
- VanGelder, Lawrence. "Theater Review. 'A Christmas Carol'" The New York Times, December 17, 2005
- Gans, Andrew. 2004 MAC Awards Announced; Mason, Sullivan, DeRoy Among Winners" playbill.com, May 18, 2004