Eighteenth-century Britain witnessed a struggle over knowledge and expertise in agriculture that has been largely neglected. This article uses the social controversies surrounding book-farming' - the practice of farming with knowledge acquired from books - to highlight the wider conflict over agricultural knowledge. The development of agricultural instructional literature gave rise to tensions between an established labour-based and an emerging book-based system of knowledge, which mapped onto social struggles over control of the intellectual powers of production. Hostility to book-farming' from practical farmers was partly a response to the threat books posed to the customary knowledge of farm workers of various kinds.