This paper presents a new study of the grammatical and social factors conditioning variable negative concord in Québec French, with a particular focus on the French spoken in Montréal. It has been observed, since at least Daoust-Blais 1975, Lemieux 1985 and Muller 1991, that negative indefinites in certain varieties of French spoken in Canada and in Europe can optionally co-occur with the sentential negation operator pas ‘not’ without creating a difference in meaning: J’ai (pas) rien contre ça ‘I have nothing against that’. The study of patterns of variation in negative concord constructions in varieties of English has received an enormous amount of attention in the field of sociolinguistics, particularly in variationist circles, and there have been numerous studies of patterns of variation in another aspect of the French negation system: the presence/absence of the preverbal clitic ne. In contrast, with the exception of Daoust-Blais 1975, Lemieux 1985, and Larrivée 2014, there has been very little quantitative investigation into the sociolinguistic factors conditioning the variable use of pas with negative indefinites. This paper therefore contributes to filling this empirical gap with a new quantitative study of variable negative concord in the Montréal 84 corpus of spoken Montréal French (Thibault and Vincent 1990). In particular, we show that the use of the concord variant (versus the bare variant) is conditioned by both social factors (age and education level) and grammatical factors (lexical identity and syntactic embedding). Furthermore, we observe that the grammatical factors that are found to significantly condition the variation found in Montréal 84 are properties that have been previously argued to play a role in the non-variable syntax of negative concord in other Gallo-Romance and Italian dialects. Therefore, in addition to shedding light on the linguistic encoding of social categories in 20th century Québec, our results shed light on the fine-grained typology of the syntax of negation in the Romance and Germanic languages.