O Pioneers! is an American opera in two acts by composer Barbara Harbach, set to a libretto by Jonathan Yordy. It is based on the 1913 novel by Willa Cather. Harbach became enamored with Willa Cather's works when commissioned by the Central Wisconsin Symphony Orchestra to write a symphony based on Cather's novel One of Ours. When given the opportunity to compose an opera, she chose O Pioneers! because she has "always been drawn to stories about strong women." Harbach adds that Cather's story "has all the elements that an opera needs: long-term loving relationships, sibling rivalry and murder."