Matthijs Siegenbeek (1774-1854) was the fijirst to hold a chair solely devoted to Dutch. While young at the time of his appointment in 1797, he would soon occupy a central position in many cultural networks of the Netherlands. He authored the fijirst offfijicial spelling of Dutch (1804) and was one of the fijirst historians of Dutch literature. This chapter discusses Siegenbeek's activities in the fijield of Dutch studies, particularly his linguistic publications. These are interpreted within the framework of cultural nationalism, and against the background of the formation of the Dutch nation-state. Throughout his career, Siegenbeek was in defence of Dutch, where Dutch should be interpreted as a cultivated, normalised, and uniform variety modelled after the written language of well-known authors, symbolically representing the Dutch nation.