The current network of protected areas in Spain has been a product of the transfer of political responsibilities from the State to the autonomous regional governments that began in the 1980s. Among other outcomes, this institutional re-arrangement triggered an unprecedented development of public policies and legislation in the field of nature conservation. In these pages we will trace the contours of a genealogy of what we would call the “institutionalization” of nature conservation, through the diachronic, comparative analysis of three case studies and their specificities: Catalonia, Andalusia and the Valencian Community. We will then expand our analysis to Portugal and, eventually, to the current international context wherein neoliberal conservation policies are expanding nowadays.