Maynard is a town in Middlesex County, Massachusetts, United States. The town is located 22 miles west of Boston, in the MetroWest and Greater Boston region of Massachusetts and borders Acton, Concord, Stow and Sudbury. The town's population was 10,746 as of the 2020 United States Census. Maynard is located on the Assabet River, a tributary of the Concord River.