This paper aims to shed light on the ideas and interests supporting the institutionalization of family agriculture in Argentina. It became a socio-political and productive category in support of a renewed national strategy of Argentina. We analyze the processes of that legitimation in the political, social and economic domains and we present the transformation of public policies regarding rural development. The change from palliative policies to supporting policies aiming to identify as a productive sector and professionalize family agriculture demonstrates the change in policy reference for rural development and shows new social representations of the agriculture in Argentina and more generally in South America. Now the family agriculture identifies itself by the multifunctional aspect of its activity. That leads to a fragmentation of the agricultural economic sector in two policy reference frameworks, one based on the family agriculture and its roles in the national development, one based on the entrepreneurial agriculture for export.