L'Assomption (The Assomption) is a regional county municipality in southwestern Quebec, Canada. The seat is in L'Assomption. The region is named for the L'Assomption River which flows through the region from the north before emptying into the Saint Lawrence River in the south of the region at Repentigny. L'Assomption is located directly north of the city of Montreal. L'Assomption is located in the Lanaudière region of Quebec.