- Authorized on April 23, 1775 in the Massachusetts State Troops as Fellows' Regiment.
- Organized in spring 1775 at Roxbury to consist of 10 companies from central Hampshire County, southern Berkshire County and Worcester County.
- Adopted on June 14, 1775 into the Continental Army and assigned to the Main Continental Army.
- Assigned on July 22, 1775 to Thomas' Brigade, an element of the Main Continental Army.
- Consolidated (less Soul's Company) on January 1, 1776 with Ward's Regiment and consolidated unit redesignated as the 21st Continental Regiment; concurrently, Soul's Company reOrganized and redesignated as Soul's Company, 6th Continental Regiment.