As a member of the Iona Players, Finn appeared in a series of leading roles, from Blanche Du Bois in A Streetcar Named Desire[1] to Sally Bowles in Cabaret.

Following her graduation, she was once again persuaded to return to Iona during post-grad summer session and was cast in the lead as Maria in West Side Story, this was her third Stephen Sondheim musical, which included roles as Marta in Company and Young Dolly in Follies.

Despite a flurry of negative reviews, Clive Barnes raved in the New York Post that "A beautifully acrid comic skit is provided by Terry Finn as a producer's wife with even less morals than taste and a turn a phrase that would cause a viper to bite out its tongue in envy," and in the New York Daily News Douglas Watt wrote "There is also good work by Jason Alexander and his gushingly imperious wife Terry Finn."

[3][4] Following a search outlined in a Broadway.com article entitled "Finding Finn," Merrily director Lonny Price recalled, "Terry was dazzling in the role of Gussie ...

[4] Robert Simonson and Kenneth Jones of Playbill.com noted that the "inclusion of lesser-known songs considerably beefed up the role of Gussie, played by Terry Finn, who is barely present on the show's famous original cast album.

"[4] Finn is interviewed in Best Worst Thing That Ever Could Have Happened, a 2016 documentary film recalling the history of the show and the later lives of its actors, directed by Lonny Price.