In July 2007, Money Magazine ranked North Haven as the eighty-sixth "best place to live" in the United States.
As of the census of 2000, there were 23,035 people, 8,597 households, and 6,490 families residing in the town. The population density was 1,108.9 people per square mile (428.2/km²). There were 8,773 housing units at an average density of 422.3/sq mi (163.1/km²). The racial makeup of the town was 92.98% White, 2.22% Black or African American, 0.09% Native American, 3.36% Asian, 0.01% Pacific Islander, 0.52% from other races, and 0.82% from two or more races. Hispanic or Latino of any race were 1.88% of the population.
There were 8,597 households out of which 31.0% had children under the age of 18 living with them, 64.2% were married couples living together, 8.1% had a female householder with no husband present, and 24.5% were non-families. 21.0% of all households were made up of individuals and 10.9% had someone living alone who was 65 years of age or older. The average household size was 2.65 and the average family size was 3.10.
In the town the population was spread out with 22.6% under the age of 18, 5.6% from 18 to 24, 27.2% from 25 to 44, 26.1% from 45 to 64, and 18.6% who were 65 years of age or older. The median age was 42 years. For every 100 females there were 93.6 males. For every 100 females age 18 and over, there were 89.7 males.
The median income for a household in the town was $65,703, and the median income for a family was $73,041 (these figures had risen to $80,450 and $90,190 respectively as of a 2007 estimate) Males had a median income of $50,843 versus $36,063 for females. The per capita income for the town was $31,870. About 2.3% of families and 3.5% of the population were below the poverty line, including 1.6% of those under age 18 and 6.4% of those age 65 or over.