Harrington Park is a borough in Bergen County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 4,664, reflecting a decrease of 76 (−1.6%) from the 4,740 counted in the 2000 Census, which had in turn increased by 117 (+2.5%) from the 4,623 counted in the 1990 Census. Harrington Park was formed on March 29, 1904, from portions of Harrington Township and Washington Township, and parts of the borough of Closter.