Delhi, originally called Deerfield, is a town in Richland Parish, Louisiana, in the United States. As of the 2000 census, the town population was 3,066.
During the American Civil War, Delhi and Monroe, the seat of Ouachita Parish, were both overcrowded with unwelcome refugees from rural areas to the east when the forces of General U.S. Grant moved into northeastern Louisiana and spent the winter of 1862-1863 at Winter Quarters south of Newellton in Tensas Parish in preparation for the siege of Vicksburg, Mississippi, not completed until July 4, 1863. Historian John D. Winters reported "strong Union sympathy" in both Delhi and Monroe.
In the 1940s, Delhi was the center of a large natural gas boom, and several functioning gas fields still surround the town.