WPA describes the group as an "expandable collective," meaning there are three core members and five non-permanent members who frequently join the big three as often as their lives and careers allow. The permanent members are Luke Bulla who played with Lyle Lovett, Sean Watkins of Nickel Creek, and Glen Phillips formerly of the alt-rock band Toad the Wet Sprocket.
They explain the term "expandable collective" on their website as follows: "We recorded our record with additional members Sara Watkins (Nickel Creek), Benmont Tench (Tom Petty and the Heartbreakers), Greg Leisz (Bill Frisell, Joni Mitchell), Pete Thomas (Elvis Costello and the Imposters), and Davey Faragher (Cracker, the Imposters). While we would love to have that complete community be present all the time, the logistics of getting all of us in the same place at the same time are fairly mind boggling, so we will usually appear as a 4 or 5 piece (listed as Core Band on the tour page), but whenever possible we will have 7 or 8 people (Expanded Band). All configurations will kick ass."
Glen Phillips – vocals, guitar
Sean Watkins – guitar, vocals
Luke Bulla – fiddle, vocals, guitar
Sara Watkins – fiddle, vocals
Benmont Tench – piano, organ
Greg Leisz – pedal steel
Pete Thomas – drums
Davey Faragher – bass
The original WPA was a government program created by President Franklin Delano Roosevelt during the Great Depression. The agency provided millions of jobs for the unemployed. Artwork remembering the WPA is a central theme of the band's website.