The management of Protected Areas, once mainly devoted to ecosystems conservation and driven by a rather radical ecologic approach, has been significantly unsettled by the paradigm of sustainable development for a decade or two. The sector of Nature conservation has now to be socially responsible and shall take in account, in its policy, the ecological, economical and cultural fields at the same time. However, the global shift towards sustainability in the management practices of Protected Areas is not always obvious, and several examples of this reservation will be successively developed here, in the three above mentioned fields. Therefore a comprehensive assessment of Protected Areas effectiveness is needed in order to legitimate the role of nature conservation in the local development prospects, with the broader aim to foster a more integrated territorial governance at the local level.