ECAs are without doubt a major factor in international trade. However, they came under severe public scrutiny when they were discovered to finance and cover projects that entailed partly serious negative con-sequences for the environment and people. Hence, a reformation and harmonization process started in order to fulfil the demands of the public and to assure that the principle of sustainability is respected by ECAs. Steps toward the creation of a fair general framework for ECAs have already been taken but however it seems that critics still are not satisfied. This book deals with the trend towards a level playing field for ECAs focusing on environmental, social and ethical principles influencing the operations and especially the project screening procedures of ECAs. A fundamental goal is to describe the development of ECAs to key elements in international trade and further to reason the emergence of the harmonization process.Regardless of still prevailing differences among ECAs, efforts made to promote sustainable development among ECAs can be considered to have achieved considerable success. However, there is still a lot of work to do.