In the wake of the Tanzimat reforms during the mid-nineteenth century, Ottoman bureaucrats began to deploy a variety of data collection and classification technologies to enhance their control over the empire’s variegated territory, assets, and people. Censuses (1831) and income registers (1840 and 1844) tracked population distribution and resources; a new Land Code (1858) streamlined landownership patterns; and a new Citizenship Law (1869) fixed the parameters according to which people were officially considered to be Ottoman citizens. While the overall scope and shortfalls of these efforts have garnered some scholarly attention, the actual ways in which they were implemented, understood, or resisted in specific localities remain largely unexamined. Using the mid-nineteenth-century seaport of Izmir/Smyrna, this paper explores how the reformist state employed modern forms of cadastral mapping and land registry to claim exclusive control over the city’s physical terrain and the people who lived and invested in it. In particular, I focus on how Izmir’s material assets and property regime became a battleground through which Ottoman bureaucrats, diplomatic missions, and local property owners staked their claims and articulated their priorities. As a cosmopolitan seaport, Izmir had long been home to foreign nationals and protégés whose extraterritorial privileges were becoming increasingly disruptive for the centralizing Ottoman state, while also undermining the Empire’s position within an emerging international state system. By indexing each property to a specific taxpayer and making ownership contingent on Ottoman nationality, modern cadastration offered a critical means for bringing under Ottoman jurisdiction individuals who had eluded its control and imposing stricter boundaries on what had previously been a porous territorial regime. The struggles over Izmir’s cadastration, which are at the core of this paper, elucidate the incipient shift from the inherently more porous imperial territoriality to the more self-contained modern state territoriality—a period of radical transformations in Ottoman history. Moreover, they reveal, on the one hand, an empire that was far more dynamic and flexible, striving to affirm its place in an increasingly state centered international order, and, on the other, numerous local groups and actors who actively participated in and engaged with the changes affecting their world.