Maryland was a proprietary colony, in the hands of the Calvert family, who held it from 1633 to 1689, and again from 1715 to 1776. George Calvert, 1st Baron Baltimore (1580–1632) is often regarded as the founder of Maryland, but he died before the colony could be organized. Thus the colonial administration began with his son:

• Cecil Calvert, 2nd Baron Baltimore, 1633–1675
  • much of the colony was under republican control from 1650 to 1658.
• Charles Calvert, 3rd Baron Baltimore, 1675–1689
  • deprived of his proprietorship for his support of James II. Died 1715
• Benedict Calvert, 4th Baron Baltimore 1679-1715
• Charles Calvert, 5th Baron Baltimore, 1715–1751
• Frederick Calvert, 6th Baron Baltimore, 1751–1771
• Henry Harford, illegitimate son of the 6th Lord Baltimore, 1771–1776