Free dance is a 20th-century dance form that preceded modern dance. Rebelling against the rigid constraints of classical ballet, Loie Fuller, Isadora Duncan and Ruth St. Denis (with her work in theater) developed their own styles of free dance and laid the foundations of American modern dance with their choreography and teaching. In Europe, Rudolf Laban, Emile Jaques-Dalcroze and François Delsarte developed their own theories of human movement and methods of instruction that led to the development of European modern and Expressionist dance.