Arnold is a census-designated place (CDP) in Anne Arundel County, Maryland, United States. The population was 23,422 at the 2000 census. Neighborhoods straddle College Parkway and Ritchie Highway. Arnold is located on the scenic Broadneck peninsula. The ZIP code is 21012.
The early settlement of Arnold, an area between the Magothy and Severn rivers, began with the farm of John Arnold. Arnold, a veteran of the War of 1812, acquired 300 acres (1.2 km2) on the north side of the Severn River.
Arnold is served by the Anne Arundel County Public School System.