The Equator Principles are a set of operational principles and standards adopted by more than 70 public and private financial institutions to manage environmental and social risks in project financing. This article assesses the impact of the voluntary framework on lending policies and practices, and the environmental and social accountability of financial institutions. It finds that the direct link between the Equator Principles and the International Finance Corporation (IFC), the World Bank Group's private sector financing division, enhances the legitimacy and potential impact of the framework. However, development of lending policies across financial institutions is greatly uneven, and the framework has not stopped lending to projects with significant environmental and social costs. Although the framework has improved relations between financial institutions and stakeholders, a lack of transparency undermines external accountability. The conclusion considers the scope for increased harmonization of environmental and social lending policies in international banking.