In Gascony and Languedoc, from the Middle Ages down to the Revolution, the word « agrier » could have several meanings related to various forms of proportional levies on the harvest, but was more often used to describe a customary fee linked to highly specific forms of land tenure. The examination of agricultural tenancy contracts, rent rolls, and customary charters from the 13th century brings to light the multiplicity of logical processes underpinning the fixation of seigniorial fees, and enfranchisement charters allow us to perceive the extent to which these forms of levies were linked to very specific social, legal and technical contexts. Once compared to what we know of sharecropping levies elsewhere in Europe, these characteristic features of agriers shed a new light on the role played by communities, agricultural practices, and modes of appropriation of the land in shaping the seigniorial levies.