For nearly two decades, the notion of "living with the semi-arid" guides the action of a significant part of civil society organizations in the semi-arid of Brazil and is included in the proposals of public policies and government actions in the region. Analyze the evolution of this concept is necessary to understand how he emerged and how he managed to steer some public policies. We show how this trajectory reflects an "institutional experimentalism", defined as a process in which new forms of governance in the relationship between government and society are tested. However, this "experimentalism" institutional needs stages that will allow its emergence. First, the notion of "living with the semi-arid" region is characterized by a "resistance" of social organization in relation to practices and interventions to combat drought. Second, the notion is gaining a wider political dimension, able to articulate a project including several sectors and social organizations in the region. Finally, we describe the characteristics of the institutional experimentalism, concluding on the interest of this notion in the reflexion of the construction of public policies.