The bookstore at Castle Clinton National Monument is located in a kiosk inside the castle's courtyard. The bookstore is run by Eastern National, a cooperating association that works with the National Park Service and has retail outlets at National Parks in more than 30 states.

All of the products, programs and publications offered to visitors in the store have a strong educational value. The profits from Eastern National activities are donated to the National Park Service and other partners to further support their educational and interpretive programs.