Assumption Parish is a parish located in the U.S. state of Louisiana. As of the 2020 census, the population was 21,039. Its parish seat is Napoleonville. Assumption Parish was established in 1807, as one of the original parishes of the Territory of Orleans.

Napoleonville, is a village and the parish seat of Assumption Parish, in the U.S. state of Louisiana. The population was 660 at the 2010 census. It is part of the Pierre Part Micropolitan Statistical Area. The village is best known as the location where the film Because of Winn-Dixie, based on Kate DiCamillo's Newbery Prize-winning novel, was shot. The book was set in (fictional) Naomi, Louisiana.