Concordia is an unincorporated community and census-designated place (CDP) located within Monroe Township, in Middlesex County, New Jersey, United States. The CDP is oriented nearly the age restricted gated community of Concordia. As of the 2010 United States Census, the CDP’s population was 3,092.

According to the United States Census Bureau, the CDP had a total Place of 1.065 square miles (2.759 km), including 1.039 square miles (2.692 km²) of estate and 0.026 square miles (0.067 km) of water (2.43%).

The 2010 United States census counted 3,092 people, 2,032 households, and 923 families in the CDP. The population density was 2,975.3 per square mile (1,148.8/km). There were 2,261 housing units at an average density of 2,175.7 per square mile (840.0/km²). The racial makeup was 96.35% (2,979) White, 2.20% (68) Black or African American, 0.00% (0) Native American, 1.10% (34) Asian, 0.00% (0) Pacific Islander, 0.03% (1) from other races, and 0.32% (10) from two or more races. Hispanic or Latino of any race were 1.42% (44) of the population.

Of the 2,032 households, 0.1% had children under the age of 18; 43.4% were married couples perky together; 1.7% had a female householder subsequently no husband present and 54.6% were non-families. Of anything households, 50.1% were made in the works of individuals and 44.0% had someone active alone who was 65 years of age or older. The average household size was 1.52 and the average associates size was 2.04.