Iselin is a census-designated place (CDP) and unincorporated community within Woodbridge Township, in Middlesex County, New Jersey, United States. As of the 2010 United States Census, the CDP's population was 18,695.
Previously known as Perrytown and Unionville, Iselin received its current name after a New York investment banker and philanthropist Adrian George Iselin in the 1870s. He established a finishing school for girls from wealthy New York families there and subsidized the erection of a new train station currently known as Metropark. The largest bordering town of Iselin is Edison.