40 Days is the debut full-length album from Canadian folk trio The Wailin' Jennys.

Although the title, 40 Days appears as a line in the song "Something to Hold Onto", and traditionally has religious significance it was chosen for another reason.

The title is actually the number of days it took the Jennys to record and refine the album and is a tribute to the experiences encountered during that time.

[citation needed] The album features three tracks contributed by each of the band's three songwriters and covers of Neil Young's "Old Man" and John Hiatt's "Take It Down".

In 2015, a cover of "One Voice" was recorded for the animal rights documentary film A Dog Named Gucci by Norah Jones, Aimee Mann, Susanna Hoffs, Lydia Loveless, Neko Case, Kathryn Calder, and Brian May.