This Article scrutinizes the potential contribution of the World Bank, as an international economic organization, to the sustainable development agenda. Analyzing the reforms in policies, procedures, and organizational structure that accompanied the Bank’s involvement in ostensibly political, non-economic matters such as human rights, environmental protection, and good governance—all of which are critical components of sustainable development—this Article contends that, contrary to the so-called mission creep argument, the evolution of the Bank’s mandate is legally defensible and normatively desirable. Instead of amending its constituent instrument, the Bank has optimized the teleological- evolutionary approach to treaty interpretation to expand and reconstruct its mandate in response to the changing needs of its clients. However, to complete its credible transformation into a “sustainable development agency,” the interpretation of its Articles of Agreement should be guided not only by the treaty parties’ intent but also by the international community’s expectations and demands. The international community’s consensus on the multidimensional character of sustainable development and the related principle of integration must be read into the Bank’s constituent instrument and must guide its development policies and operational activities.