This article argues that with the original emphasis on dialectal variation, using primarily literary texts from various regions, analysis of Old French has routinely neglected social variation, providing an incomplete picture of its grammar. Accordingly, Old French has been identified as typically featuring e.g. “pro-drop”, brace constructions, and single negation. Yet examination of these features in informal texts, as opposed to the formal texts typically dealt with, demonstrates that these documents do not corroborate the picture of Old French that is commonly presented in the linguistic literature. Our reconstruction of Old French grammar therefore needs adjustment and further refinement, in particular by implementing sociolinguistic data. With a broader scope, the call for inclusion of sociolinguistic variation may resonate in the investigation of other early languages, resulting in the reassessment of the sources used, and reopening the debate about social variation in dead languages and its role in language evolution.