The Massachusetts Bay Colony (sometimes called the Massachusetts Bay Company, for the institution that founded it) was an English settlement on the east coast of North America in the 17th century, in New England, centered around the present-day cities of Salem and Boston. The area is now in the Commonwealth of Massachusetts, one of the 50 United States.

Prior to 1753, England and its colonies used the Julian calendar, and the dates for all events in England and its colonies are reported using this calendar, unless specified otherwise. When using the Julian calendar, all dates from January 1 to March 22 must be reported using the "double date" notation, such as 1628/29.