Adelphia is an unincorporated area located within Howell Township in Monmouth County, New Jersey. It was previously known as Turkey. The community has a total area of 35.41 km² and a population of 17,000 people. The community is spread in Howell Township, Colts Neck Township, Farmingdale, and Freehold Township.
The economy is based on local businesses, professional services, sales and service, and production, construction and transport of materials.