In this paper we present a benchmarking of European banks and service organizations regarding the integration of sustainability in their policies, strategies, products, services and processes. Using a multi level analysis starting with a screening from 127 organizations and ending with in depth interviews with eight organizations we could analyze both the state of the art and the best in class integration of sustainability. We analyzed the business fields credit business, asset management, and investment banking. For every business field we present the leaders in sustainability integration. In addition we found five models of successful integration of sustainability into the banking business as they are the event related sustainability integration, sustainability as a new banking strategy, sustainability as value driver, sustainability as public mission, and sustainability as a requirement of clients. Different banks can use those models to implement sustainability in their business. As successful strategies to implement sustainability in banks and financial institutions we found the implementation by a pilot group, the change of the business strategy, the problem oriented strategy, and the shifting of responsibility and competences for sustainability from staff to line management. Thus the principles of sustainable banking we could extract out of the study are first, the integration of sustainability into the core business of the bank, second, the integration of sustainability into the general business strategy, and third to deal with sustainability not as a soft factor, but as a measurable business result.