New Netherland, or Nieuw-Nederland in Dutch, was the 17th-century colonial province of the Republic of the Seven United Netherlands on the East Coast of North America. The claimed territories were the lands from the Delmarva Peninsula to extreme southwestern Cape Cod. The settled areas are now part of the Mid-Atlantic States of New York, New Jersey, Delaware, and Connecticut, with small outposts in Pennsylvania and Rhode Island. The provincial capital, New Amsterdam, was located at the southern tip of the island of Manhattan on upper New York Bay.

The colony was conceived as a private business venture to exploit the North American fur trade. During its first decades, New Netherland was settled rather slowly, partially as a result of policy mismanagement by the Dutch West India Company (WIC), and conflicts with Native Americans. The settlements of New Sweden developed on its southern flank and its northern border was re-drawn in recognition of early New England expansion. During the 1650s, the colony experienced dramatic growth and became a major port for trade in the North Atlantic. The surrender of Fort Amsterdam to English control in 1664 was formalized in 1667, contributing to the Second Anglo–Dutch War. In 1673 the Dutch re-took the area, but later relinquished it under the 1674 Treaty of Westminster ending the Third Anglo-Dutch War.