Monmouth is a town in Kennebec County, Maine, United States. Monmouth is included in the Lewiston-Auburn, Maine metropolitan New England city and town area. The population was 4,066 at the 2022 census.

Kennebec County is a county located in the South-central portion of the U.S. state of Maine. At the 2020 census, the population was 123,642. Its county seat is Augusta, the state capital. The county was established on February 20, 1799, from portions of Cumberland and Lincoln Counties. The name Kennebec comes from the Eastern Abenaki /kínipekʷ/, meaning "large body of still water, large bay."