Chapter 2shows that the wide diversity of agricultural forms stems from the political and social structures rooted in historical trajectories, where representations have been forged by power relations and the dissemination of technical progress. This diversity and its reasons invite us to make an effort, necessarily reductive, to define, characterize and measure family farming models, and to clarify what makes them a political and analytical category. To name the production units of the agricultural sector, several categories are mobilized by actors, all of which pertain to different professional spheres but do so in interaction with each other. There are four broad domains in interaction within which categories are gener- ated and used to describe agricultural production actors.