Even if European and French policies aim at reducing agricultural land consumption for urban development, the equivalent of one French department area is built each seven years. The implementation of French land use planning policies is supposed to integrate the cooperation of agriculture professionals, as a governance form of public intervention. Considering this, we assume that there are some learning failures in the cultural integration between politics and agricultural sectors which may explain some misinterpretations of farming systems issues. In this paper, we expose a method to unravel farming systems dynamics in the context of urban sprawl, as understanding this means integrating on one hand the complexity of agricultural working systems, on the other hand the complexity of the different impacts of urban sprawl on these systems. With this aim in view, we present a new way to study farmers’ strategies. Our approach is based on an analysis of farmers’ decisions, coupled with their motivations. We identified five action levers and four distinct farmers’ rationales with regard to land management decisions, and also their interdependencies. This method could also be used to study other types of farming systems’ structural changes.