Uncasville is an area in the town of Montville, Connecticut, United States. It is a village in southeastern Montville, at the mouth of the Oxoboxo River. The name is now applied more generally to all of the east end of Montville, which is the area served by the Uncasville ZIP Code.
In 1994 the federal government officially recognized the Mohegan Indian Tribe of Connecticut, which had historically occupied this area. That year Congress passed the Mohegan Nation (Connecticut) Land Claim Settlement Act. It authorized the United States to take land into trust in northeastern Montville for the Mohegan tribe's use as a reservation. Since gaining a reservation, in 1996 the tribe developed the Mohegan Sun casino resort. It has also built the Mohegan Sun Arena on their land. The Mohegan are one of the Native American peoples of the Algonquian languages family.