In the eighteenth century, the Rum Orthodox Patriarchate of Istanbul underwent a series of changes that were the result of eighteenth-century economic and social developments in Ottoman society. This study investigates the changing fortunes of the Patriarchate in the eighteenth century through a contextualization of these events in their Ottoman background. Despite the conclusions of previous historiography, the patriarch appears as more than a mere mültezim or a milletbaşı / ethnarch, functioning instead more as a religious leader of the Ottoman Orthodox community who acted according to the Ottoman principles of nizam [order] and the safety of the mal-ı miri. These two principles were an important part of the discourse of negotiations between the Patriarchate and the Porte in the eighteenth century, and were used efficiently by both sides. Many internal and external actors were involved in the events, including archons, Catholics, Protestants, the esnaf, and merchants both Muslim and non-Muslim. A case study of the mid-eighteenth-century Patriarch Kyrillos V Karakallos demonstrates how one patriarch effectively struggled to consolidate his authority vis-à-vis his opponents. Following the patriarchal term of Karakallos, the system of gerondismos was established, as a result of which the Patriarchate had come, by 1763, to be represented before the Porte as a collective identity. Overall, far from being a static entity, the Patriarchate appears to have been an active subject in the urban setting of the imperial city, engaged in a relationship with the financial and social networks of Ottoman society.