is a town in New Haven County, Connecticut, United States. The population was 13,906 at the 2000 census.
According to the United States Census Bureau, the town has a total area of 26.6 square miles (69.0 km²), of which 24.9 square miles (64.5 km²) is land and 1.7 square miles (4.5 km²) (6.49%) is water. Neighboring towns are Wallingford and Durham to the north, Guilford to the east, Branford to the south, and North Haven and East Haven to the west.
Much of the town's acreage is dominated by Totoket Mountain, part of the Metacomet Ridge, a mountainous traprock ridgeline that stretches from Long Island Sound almost to the Vermont border. The north side of Saltonstall Mountain is also located in North Branford. Totoket Mountain contains Lake Gaillard, a reservoir managed by the South Central Connecticut Regional Water Authority (SCCRWA). The SCCRWA maintains a network of hiking trails on Totoket Mountain in the Big Gulph area of Northford.