North Caldwell was incorporated by an Act of the New Jersey Legislature on March 31, 1898, from portions of Caldwell Township (now known as Fairfield Township). In 1982, North Caldwell became a township to take advantage of federal revenue sharing policies. Effective January 1, 1992, it again became a borough.
New Jersey Monthly magazine ranked North Caldwell as its 25th best place to live in its 2008 rankings of the "Best Places To Live" in New Jersey.
As of the census of 2000, there were 7,375 people, 2,070 households, and 1,834 families residing in the borough. The population density was 2,464.6 people per square mile (952.3/km). There were 2,108 housing units at an average density of 704.5/sq mi (272.2/km). The racial makeup of the borough was 79.63% White, 14.51% African American, 0.03% Native American, 4.71% Asian, 0.26% from other races, and 0.87% from two or more races. Hispanic or Latino of any race were 2.16% of the population.
There were 2,070 households out of which 42.0% had children under the age of 18 living with them, 80.5% were married couples living together, 5.9% had a female householder with no husband present, and 11.4% were non-families. 9.6% of all households were made up of individuals and 4.8% had someone living alone who was 65 years of age or older. The average household size was 3.02 and the average family size was 3.23.
In the borough the population was spread out with 23.1% under the age of 18, 8.7% from 18 to 24, 31.0% from 25 to 44, 26.4% from 45 to 64, and 10.9% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 118.5 males. For every 100 females age 18 and over, there were 124.2 males.
The median income for a household in the borough was $117,395, and the median income for a family was $125,465. Males had a median income of $87,902 versus $47,904 for females. The per capita income for the borough was $48,249. About 0.8% of families and 1.2% of the population were below the poverty line, including 2.4% of those under age 18 and none of those age 65 or over.
The above demographics derived from the 2000 census are skewed by the presence of the Essex County Jail Annex which was in North Caldwell until 2004. With the construction of the new Essex County Jail, the facility in North Caldwell has since been consolidated with the new facility in Newark.