The World Bank Group's (WBG) environmental and social safeguards are at the center of a heated debate regarding their legitimacy. They also face important implementation problems. Nevertheless, these safeguards are instrumental vectors of sustainable development in Recipient countries through their insertion as conditionality in loan agreements. The question at stake is therefore how to reinforce the safeguards as effective vectors of sustainable development while avoiding sovereignty infringement and solving issues of noncompliance. For this purpose, the dissertation first aims at posing a diagnostic of the problems faced by this conditionality. Then, using three case studies, it proposes several avenues for change, such as a Human Rights-based harmonization of safeguards across Multilateral Development Banks, institutional changes in the WBG to strengthen the support for environmental and social protection and a strict assessment of the suitability of the Recipient's context for safeguards' implementation.