This book aims to explain the specifics of the EUs approach to Iran with a special focus on the 2015 Nuclear Deal. It takes into account both the complexity of European foreign policy, in particular within transatlantic relations, and Irans (aspired) place in the international order. It informs the reader about the special negotiation format that included a number of world powers as well as multilateral bodies such as the International Atomic Energy Agency (IAEA) and the UN Security Council and highlights the challenges the Deal now faces.