"Why Not" is a song recorded by American actress and singer Hilary Duff. It was written by Charlie Midnight with Matthew Gerrard, who also produced the song. It was released on March 21, 2003, by Walt Disney Records as the first single from The Lizzie McGuire Movie soundtrack. The version of the song on Duff's 2003 album Metamorphosis features different lyrics in the first verse.

Hilary Erhard Duff is an American actress, singer, author and businesswoman. She is the recipient of various accolades, including seven Nickelodeon Kids' Choice Awards, four Teen Choice Awards, and two Young Artist Awards. She began her acting career at a young age, quickly being labeled a teen idol as the title character in the Disney Channel comedy series Lizzie McGuire (2001–2004) and in the film based on the series, The Lizzie McGuire Movie (2003).