From the start, Turkey's aspirations to join the European Union aroused considerable opposition. Recently, the debate has focused increasingly on supposed disparities in the spheres of culture, politics or mentality, implying that this Muslim country would not be able to comply with European norms and values. Supporters of Turkey's candidacy, on the other hand, have pointed out that Turkey has always been an important element of the European balance of power and was, in the nineteenth century, even a member of the Concert of Europe. Both sides invoke history to justify their arguments. The present paper examines the evolution of the European state system and the major stages in the history of the Turkish–European relationship, with a view to arriving at a more balanced judgement. It can be shown that new concepts, such as state interest and balance of power, had already begun in the sixteenth century to undermine the old theological worldview and, beginning with the eighteenth century, the Ottoman Empire was treated – at least de facto – as an actor that observed fully the norms of European public law (jus publicum Europeum). However, a de jure recognition of the Empire's status had to wait until the Treaty of Paris (1856), but even then it did not include an effective guarantee of Ottoman territorial integrity.