[1] The villages of Chesterfield, Mohegan, Oakdale, and Uncasville are located within the town; the latter two have their own ZIP Codes.

In the 17th century, when English settlers arrived, southeastern Connecticut was the scene of rivalry between the Pequot people, the dominant Native American group in the New London area, and the newly independent Mohegan.

For defense against the Pequot, the Mohegan sachem Uncas had established a fortified village on a promontory above the Thames River within what is now the town of Montville.

The first grants were made by Uncas in 1658 to Richard Houghton and James Rogers, consisting of valuable farms along the river.

[2] By 1703 the area between the Oxoboxo River and Norwich (now part of the town of Montville) was annexed by New London.

Part of Montville is also treated by the U.S. Census Bureau as a census-designated place called Oxoboxo River.

In the seventeenth century, the colony of Connecticut granted them a 700-acre (2.8 km2) reservation, located north of the present-day village of Uncasville.

Although the reservation is within the borders of the town of Montville, the tribe is federally recognized as a sovereign nation not subject to local or state laws.

Since at least the 1990s, people of Chinese descent have moved into the area drawn either by the work available at Mohegan Sun and the rising prices in the Northeast's Chinatowns.

[12] In return for building the plant, the company demanded that the state guarantee NRG long-term contracts for buying the electricity it generates and pick NRG's proposal over other plans for building new power plants in the state.

At the time of NRG's proposal, only 18 plants in the world and two in North America used the Integrated Gasification Combined-Cycle technology which the company suggested.

NRG Energy announced plans on August 5, 2013, to add fuel cells, solar and biomass conversion to the plant[13]