Braintree, officially the Town of Braintree, is a municipality in Norfolk County, Massachusetts. It is officially known as a town, but Braintree is a city with a mayor-council form of government, and it is considered a city under Massachusetts law. The population was 39,143 at the 2020 census. It is part of the Greater Boston area with access to the MBTA Red Line and is a member of the Metropolitan Area Planning Council's South Shore Coalition.