Northern Valley Regional High School at Demarest is a comprehensive four-year public high school serving students from several municipalities in Bergen County, New Jersey, United States. The high school serves students from the suburban communities of Closter, Demarest, and Haworth. The school is one of two high schools that are part of the Northern Valley Regional High School District, the other being Northern Valley Regional High School at Old Tappan, which serves students from Harrington Park, Northvale, Norwood, and Old Tappan, along with students from Rockleigh, who attend as part of a sending/receiving relationship.

Closter is a borough in Bergen County, in the U.S. state of New Jersey. As of the 2020 United States census, the borough's population was 8,594, an increase of 221 (+2.6%) from the 2010 census count of 8,373, which in turn reflected a decline of 10 (−0.1%) from the 8,383 counted in the 2000 census.