The Paulins Kill (also known as Paulinskill or Paulinskill River) is a 41.6-mile (66.9 km) tributary of the Delaware River in northwestern New Jersey in the United States. With a long-term median flow rate of 76 cubic feet of water per second (2.15 m³/s), it is New Jersey’s third-largest contributor to the Delaware River, behind the Musconetcong River and Maurice River. The Paulins Kill drains an area of 176.85 square miles (458.0 km2) across portions of Sussex and Warren counties and 11 municipalities. The Paulins Kill flows north from its source near Newton, and then turns southwest. The river sits in the Ridge and Valley geophysical province.
The Paulins Kill was a conduit for the emigration of Palatine Germans who settled in northwestern New Jersey and northeastern Pennsylvania during the colonial period and the American Revolution. Remnants of their chiefly agricultural settlement are still found in local architecture, cemeteries, farms and mills, and the area remains largely rural to this day.
Flowing through rural sections of Sussex and Warren counties, the Paulins Kill is regarded as an excellent venue for fly fishing. The surrounding area has hiking, other forms of recreation such as observation of a multitude of species of birds and other wildlife.