From the middle of the seventeenth century until 1853, the Japanese shogunal government virtually isolated Japan from the rest of the world. Only the Chinese and the Dutch were allowed to maintain a trading post in the harbour of Nagasaki. All dealings with the Dutch traders were subject to strict controls, and the interpreters that were trained to liaise with them had to swear a blood oath to secrecy. Nevertheless, information regarding the scientific and technological advances that were made in the West during this period managed to penetrate this barrier, and eventually grew, to some extent with official sanction, into a popular branch of scholarship known as rengeku, literally 'Dutch learning'. Since nearly all of the academic knowledge that reached Japan from the West arrived in written Dutch, the Dutch language became the language of science in Japan during this period, and a necessary subject of study for allrangaku scholars. This thesis is the first study in English that examines the development of the study of the Dutch language in Japan during the period through an analysis of the textbooks and dictionaries that were produced in Japan. The works selected for this study are those considered to be representative of, or significant to, the development of the study of Dutch and attendant increase of awareness of Western linguistic concepts, many of which were imposed, for better or worse, on the Japanese language. Other, less influential documents, are occasionally also discussed, to demonstrate the false trails and misunderstandings that can emerge when a foreign language is presented to students without the benefit of demonstrated current and practical usage. Initially Dutch language study was restricted to the development of skills among the Dutch interpreters in Nagasaki, who compiled word lists for personal use. These lists developed from primitive and limited glossaries into relatively sophisticated Chinesestyle lexicons and finally evolved into the large-scale Haruma dictionaries of the early nineteenth century. Early attempts at understanding the structures of the Dutch language, both by interpreters and academics, failed to provide practical insights. An important i breakthrough was achieved when retired interpreter Shizuki Tadao (1760-1806) began to produce translations of Nederduytsche Spraakkonst('Dutch Grammar') by William Sewel, and applied Western linguistic concepts to the Japanese language. This new understanding gave rise to a consistent structural approach to the study of Dutch, as a result of which language study became more consistent and translations more sophisticated. Although the end of national isolation in the middle of the nineteenth century meant that the study of Dutch was soon abandoned in favour of other European languages, many words in the Japanese language, particularly in relation to science and technology, are of Dutch origin. More importantly, many of the principles and terminology the Japanese use to define the structures of their language stem from the insights into Western linguistics gained during those final decades of the period of national isolation.