Beauregard Parish is a parish located in the U.S. state of Louisiana. As of the 2020 census, the population was 36,549. The parish seat is DeRidder. The parish was formed on January 1, 1913.

DeRidder is a city in, and the parish seat of, Beauregard Parish, Louisiana, United States. A small portion of the city extends into Vernon Parish. As of the 2010 census DeRidder had a population of 10,578. It is the smaller principal city of the DeRidder-Fort Johnson South CSA, a Combined Statistical Area that includes the Fort Johnson South and DeRidder micropolitan areas, which had a combined population of 87,988 at the 2010 census.