"Best Day of My Life" is a song written by Zac Barnett, Dave Rublin, Matt Sanchez and James Adam Shelley of the American indie rock band American Authors, with co-writers Aaron Accetta and Shep Goodman. The song was originally recorded for release as a single by Mercury Records and Island Records on March 19, 2013. The track, produced by Aaron Accetta and Shep Goodman, later appeared as the second track on the band's third extended play, and first under the American Authors name, American Authors, and the third track on their debut studio album, Oh, What a Life.