Partitive constructions involving human referents (e.g. one of the students) may give rise to gender agreement mismatches between set and subset in some languages. Native speakers have intuitions about whether such mismatches are acceptable or not. Gender mismatches in partitive constructions have not received much attention in the literature yet, but are particularly interesting in the light of the ongoing discussions on gender equal language, which challenge the existing gender systems in many languages. This dissertation investigates which factors influence the acceptance of gender mismatches by speakers of French and German and discusses those factors in the light of the ongoing discussions on gender equal language. Furthermore, it proposes a novel theoretical explanation for the observed facts within the framework of Generative Grammar. As such, this dissertation does not only give insight into an understudied phenomenon, gender agreement in partitive constructions, but also contributes to our understanding of how social factors may influence language and eventually could cause language change.