Mayflower Compact, in U.S. colonial history, an agreement providing for the temporary government of Plymouth Colony. The compact was signed (1620) on board the Mayflower by the adult male passengers; it created the first American settlement that was based upon a social contract. In it, the colonists combined together in a "civil Body Politick" whose purpose was to frame just and equal laws for the general good of the colony. The compact remained the basis of government in Plymouth for ten years, and all later governments in the colony developed out of the compact.