Founded to train high school teachers through the "agrégation", ENS is now an institution training researchers, professors, high-level civil servants, as well as business and political leaders. It focuses on the association of training and research, with an emphasis on freedom of curriculum. The school's resources are equally divided between its "Letters" (social and human sciences and literature) and its "Sciences" (natural sciences and mathematics) sections. The school's fifteen departments and its 35 units of research ("unités mixtes de recherches" or "UMR" in French) work in close coordination with other public French research institutions such as the CNRS.