Calico Horse was formed by members of the Clock Work Army, along with Goodbye Blue Monday singer Matt Mournian and Emily Neveu as keyboardist/guitarist. Most locals consider the band to be Clock Work Army under a new name.

Neveu and guitarist Scott Wheeler (Cuckoo Chaos) began writing the songs that were to be Clock Work Army's first album. Wheeler, however, moved Portland, and Neveu began working with producer Pall Jenkins, of the Black Heart Procession. Calling themselves Calico Horse, the group was originally rounded out with bassist Dave "Petti" Pettijohn, singer/guitarist Matt Mournian, and drummer Tom Peart (no relation to Rush's drummer). By summer 2008, the band had pared down to a trio: Neveu, Pettijohn, and Peart.

 Calico Horse's debut album Mirror was recorded by Pall Jenkins. The group was nominated for Best New Artist at the 2008 San Diego Music Awards. In summer 2008, bassist Dave Pettijohn went on tour with Vampire Weekend as a guitar-tech.

Guitarist Matt Mournian announced in early 2009 that he was forming a new group with Greg Russell (Lowcloudcover) called This is Not My Life.