This song was introduced by Marjorie Gateson and John E. Hazzard in For Goodness Sake at the Lyric Theatre in New York City on February 20, 1922. Gene Kelly and Oscar Levant sang it in the 1951 film An American in Paris.
When this was written, Ira Gershwin was still using a pseudonym so as not to cash in on his brother's growing fame. The name he chose was Arthur Francis. Arthur was for his (and George's) younger brother. Francis came from the youngest Gershwin sibling, sister Frances.
In the film An American in Paris, director Vincente Minnelli sought to rescue three fine Gershwin songs from oblivion. He was successful with “By Strauss” (1936) and “Love is Here to Stay” (1937) but the third, “Tra-La-La,” somehow missed beatification—and that is a shame, for it is a masterpiece, one with the happy energy of a fine children's song. The unusual eighteen-bar length of the verse (“Am I happy?”) is due to the fact that after each phrase Gershwin provides a quarter note rest where, normally, one would expect rests lasting three quarter notes. Had the longer rests been used, the verse would be twenty bars long. But this tailgating effect adds to the tune's childlike breathlessness. The refrain (“This time it's really love”) is a very warm, endearing thirty-two bar ABAC tune. It has a simplicity that seems to have been born of musical depth and experience.
The Gene Kelly/Oscar Levant performance can be seen at: