The community had been garrisoned as an outpost in the French and Indian Wars of the 1740's. The initial grants to settlers were of 60-acre parcels and in the Colonial period the town fit the description of a poor agrarian community. By 1820, Westminster's diversity of religious affiliation was great enough to force the town to stop supporting a single minister with public taxes. There were Armianists, Unitarians, Congregationalists, Baptists, Methodists and Universalists in the town.

The community took a moderate position during Shays Rebellion, recommending release of the insurgents who had been captured but registering its opposition to the court system. The new road to Fitchburg was built in 1835 and the Vermont and Massachusetts Railroad reached town in 1848. By 1900 there was East-West electric streetcar service established from Fitchburg to Gardner through Westminster center.

In the early 20th century, townspeople made chairs and manufactured paper while an unusually large influx of Finnish immigrants took over the old farms in town and settled in to an agricultural life. Suburban development of the town on attractive lakeside sites and in sections of town with Wachusetts Mountain views has been part of its modern day growth.

Westminster Mass is located in North central Massachusetts, bordered by Ashburnham on the north, Fitchburg and Leominster on the east, Princeton and Hubbardston on the south, and Gardner on the west. Westminster is 6 miles west of Fitchburg, 24 miles north of Worcester, 53 miles northwest of Boston.