Westfield is a city in Hampden County, in the Pioneer Valley of western Massachusetts, United States. Westfield was first settled in 1660. It is part of the Springfield, Massachusetts Metropolitan Statistical Area. The population was 41,094 at the 2010 census.
The area was originally inhabited by the Pocomtuc tribe, and was called Woronoco (meaning "the winding land"). Trading houses were built in 1639–40 by settlers from the Connecticut Colony. Massachusetts asserted jurisdiction, and prevailed after a boundary survey. In 1647, Massachusetts made Woronoco part of Springfield. Land was incrementally purchased from the Native Americans and granted by the Springfield town meeting to English settlers, beginning in 1658. The area of Woronoco or "Streamfield" began to be permanently settled in the 1660s. In 1669, "Westfield" was incorporated as an independent town; in 1920, it would be re-incorporated as a city.