Abstract: A flexible concrete form which can be arranged to provide both straight and curved configurations, and is adapted to flex both horizontally and vertically. The form includes a face panel and upper and lower flanges having lips on their back edges. An intermediate rib spaced below the upper flange provides a ledge on which a rigid core member can be installed to enhance the rigidity for straight areas. The upper and lower flanges have aligned openings for receiving stakes used to anchor the form to the ground. The form is preferably constructed from polyethylene, polyvinyl chloride, or polybutylene because of the strength and flexibility of these materials as well as their ability to release from concrete without the need for scraping or release agents.