The charter of Massachusetts Bay was one of the New World’s first attempts to establish self-government in the English colonies of North America. In this case, the Massachusetts Bay Company, a joint-stock company resident in England, whose membership included merchants and landed gentry, received a charter from the Crown. The government of the company and the extent of its authority were clearly stated in the charter, with an unstated premise that the management of the company and thus the charter itself would remain in England.

However, a group of Puritans within the Massachusetts Bay Company adopted a pledge known as the Cambridge Agreement, in which they stipulated that they would not only migrate to the New World but also carry the charter with them. This last step was taken to assure those Puritans in the company who settled in New England that they would retain control of company management. By bringing the charter to America, the Puritans took the first step in transforming Massachusetts Bay from a trading company into a commonwealth, because the charter became the constitution of the colony.