Falsettos is a sung-through musical with a book by William Finn and James Lapine, and music and lyrics by Finn. The musical consists of March of the Falsettos (1981) and Falsettoland (1990), the last two installments in a trio of one-act musicals that premiered off-Broadway. The story centers on Marvin, who has left his wife to be with a male lover, Whizzer, and struggles to keep his family together. Much of the first act explores the impact his relationship with Whizzer has had on his family. The second act explores family dynamics that evolve as he and his ex-wife plan his son's bar mitzvah, which is complicated as Whizzer comes down with an early case of AIDS. Central to the musical are the themes of Jewish identity, gender roles, and gay life in the late 1970s and early 1980s.

Musical theatre is a form of theatrical performance that combines songs, spoken dialogue, acting and dance. The story and emotional content of a musical – humor, pathos, love, anger – are communicated through words, music, movement and technical aspects of the entertainment as an integrated whole. Although musical theatre overlaps with other theatrical forms like opera and dance, it may be distinguished by the equal importance given to the music as compared with the dialogue, movement and other elements. Since the early 20th century, musical theatre stage works have generally been called, simply, musicals.