The Little River is a 7.4-mile-long (11.9 km) river in the White Mountains of New Hampshire in the United States. It is a tributary of the Ammonoosuc River and part of the Connecticut River watershed. The Little River rises in the White Mountain National Forest in a small cirque in the Twin Range, with Zealand Mountain to the east, Mount Guyot to the south, and South Twin Mountain to the west. The river flows north into the town of Bethlehem, through a deep valley between North Twin Mountain to the west and Mount Hale to the east. Eventually the river enters the town of Carroll near the community of Twin Mountain, passes under U.S. Route 3, and ends at the Ammonoosuc River.