The European Union as a prominent regional organization is increasingly expected to contribute positively in terms of the promotion of certain values, both by European Union citizens and by the international community. These values include the promotion and development of international law, including international humanitarian law. The focus of this Article is on the influence, actual and potential, of the European Union in terms of promoting humanitarian law externally, and on ensuring respect of humanitarian law by third States. It briefly discusses the evolution of the duty to ensure respect and outlines the relevance of international humanitarian law to the external action of the European Union. The European Union Guidelines on Promoting Compliance with International Humanitarian Law are introduced and the background, content, and potential are explored. While not constituting binding law, these guidelines represent the position of the European Union in relation to promoting humanitarian law externally and reflect the responsibilities of European Union Member States with regard to ensuring respect for humanitarian law.