Abstract: Folk high schools are uniquely Scandinavian institutions for adult higher education. From the beginning to the end of the 19 century, a remarkable movement of folk high school took place in Nordic countries. The movement went through three major phases within a century: enlightenment, early practice and expansion. The folk school movement not only brought a boom in Nordic adult higher education, but also had far reaching influence on educational and social secularization, massification and modernization in Nordic countries.