His topics have included the gay and Jewish experiences in contemporary America, and also family, belonging, sickness, healing, and loss.

In Trousers, March of the Falsettos, and Falsettoland all chronicle the lives of the character Marvin; his ex-wife, Trina; his boyfriend, Whizzer; his psychiatrist, Mendel; and his son, Jason.

[6] That musical, A New Brain, starred Malcolm Gets, Kristin Chenoweth and Chip Zien, and premiered Off-Broadway at the Lincoln Center Theater in 1998.

"[9] Another student of Gerald Dyer, Alison Fraser, found fame on Broadway, collaborating with Finn in the original casts of In Trousers and March of the Falsettos.

Finn had another Broadway success with The 25th Annual Putnam County Spelling Bee, for which he wrote both music and lyrics.

Sizzle was a coming of age musical about college students but concluded in an unusual way with the star of the show, played by J. Tyler Griffin, Jr., dying in an electric chair.

The opening night cast featured Hunter Foster (Richard), Malcolm Gets (Frank), Dick Latessa (Grandpa), Taylor Trensch (Dwayne), Georgi James (Olive), and Jennifer Laura Thompson (Sheryl).

[16] The ensemble, who Jay Irwin wrote "...took the small parts they were given and ran with them, almost right out of the theater as each of them brilliantly played the comedic relief to the family's "straight man"", starred Bradley Dean, Carmen Ruby Floyd, Eliseo Roman, Andrew Samonsky, Sally Wilfert, and Zakiya Young.

[18] Finn's frequent collaborators include librettist James Lapine, director Graciela Daniele and singers/actors Stephen Bogardus, Carolee Carmello, Stephen DeRosa, Alison Fraser, Keith Byron Kirk, Norm Lewis, Michael Rupert, Mary Testa, Christian Borle and Chip Zien.

Finn was one of a selected few composers who contributed to the song cycle Stars of David which premiered in October 2012 at the Philadelphia Theatre Company.

[6][21] Notwithstanding, it saw its first full production in 2018 at the Barrington Stage Company with Putnam librettist Rachel Sheinkin penning the book.

[6] He is gay, and lives with his life partner, Arthur Salvadore, in New York City[24] and Pittsfield, Massachusetts, where he is a composer and writer.

[25] He is the co-founder and artistic producer of the Musical Theatre Lab at the Barrington Stage Company in Pittsfield, Massachusetts, established in 2006.