Assumption Parish (French: Paroisse de l'Assomption) is a parish located in the U.S. state of Louisiana, and was formed in 1807 as an original parish of the Louisiana Territory. Its parish seat is Napoleonville. In 2000, its population was 23,388. Assumption is one of the 22 Acadiana parishes. Its major product is sugarcane. In proportion to its area, Assumption Parish produces the most sugar of any parish of Louisiana.