This paper analyzes the impact of four major financial sector sustainability codes of conduct, the UN Environmental Programme Finance Initiative, the UN Principles for Responsible Investment, the Equator Principles and the Global Alliance for Banking on Values with regard to their impact on the sustainability of their members. The codes of conduct focus on the integration of environmental, social and governance criteria into financial decision making in lending, investment, asset management and project finance. corporate sustainability voluntary codes of conduct have a positive impact on their members. The effectiveness, however, depends on the quality and content of a code, as well as on implementation and compliance mechanisms.