This article offers the first complete critical edition and study of the text known as 'Domestic Economy', a late-fourteenth-century Anglo-French vocabulary and guide to household accounting found in London, British Library, MS Harley 4971, much of the content of which is ‘grafted’ from Walter de Bibbesworth’s thirteenth-century rhymed vocabulary, the 'Tretiz'. The Domestic Economy demonstrates that the 'Tretiz' enjoyed currency within the professional domains of later medieval England, and in the process challenges straightforward typologies of French-language didacticism in medieval England as either linguistic or practical.