Harbach collaborated as lyricist or librettist with many of the leading Broadway composers of the early 20th century, including Jerome Kern, Louis Hirsch, Herbert Stothart, Vincent Youmans, George Gershwin, and Sigmund Romberg.

[2] He attended the Salt Lake Collegiate Institute, transferring to Knox College, in Galesburg, Illinois, where he was a friend of Carl Sandburg, joined Phi Gamma Delta fraternity, and graduated in 1895.

[citation needed] In 1902, he spotted an advertisement for a new Joe Weber and Lew Fields musical with a picture of star Fay Templeton.

They received their first chance to have a complete show produced on Broadway when Isidore Witmark asked Hoschna, his employee, to serve as composer for a musical version of Mary McIntire Pacheco's play Incog.

With Witmark and Charles Dickson writing the libretto, the resulting show was Three Twins, which opened in 1908 and ran for 288 performances (Harbach was paid a hundred dollars for his work).

[1] Harbach and Hoschna's score was augmented with interpolations, including the popular hit "Put Your Arms Around Me, Honey" by Albert von Tilzer and Junie McCree.

Producer Arthur Hammerstein asked Harbach in 1912 to serve as librettist for a new operetta called The Firefly, to be composed by Rudolf Friml.

[2] The success of The Firefly led to ten more musical collaborations for librettist Harbach, composer Friml, and producer Arthur Hammerstein, including High Jinks (1913) and Katinka (1915).

Harbach would then collaborate with composer Youmans, co-lyricist Irving Caesar, and co-librettist Frank Mandel on the 1925 hit musical comedy No, No, Nanette.

Harbach first collaborated with Broadway composer Jerome Kern on Sunny (1925), and they would continue to work together on subsequent musicals, including Criss Cross (1926), The Cat and the Fiddle (1931), and Roberta (1933).

The Cat and the Fiddle was especially notable, as Harbach (writing both book and lyrics) and Kern aimed to create a modern operetta set in contemporary Brussels "in which music and story were indispensable to each other.

[10] He collaborated as lyricist or librettist with many of the leading Broadway writers and composers of that era, including Oscar Hammerstein II, Jerome Kern, Louis Hirsch, Herbert Stothart, Vincent Youmans, George Gershwin, and Sigmund Romberg.