Drawing on a broad range of primary sources in Ottoman Turkish, Arabic, and English, such as governmental correspondence, travelogues, and local petitions this paper explores the connections between Ottoman politics of knowledge production and imperial governance in the Province of Yemen, one of the most strongly contested frontier regions of the empire during the late 19th and early 20th centuries. I focus on the struggles between Ottoman bureaucrats and local actors, including “tribal” leaders and the Zaydi imams, over the issue of what constituted knowledge of local society and what it meant to fashion governmental practices according to it. Historians have shown that new types of population counts and cadastral surveys played a key role in government efforts to build a more intrusive Ottoman state from the reign of Mahmud II (1808-1839). However, knowledge production in Ottoman frontier regions where neither censuses nor cadastral surveys could be carried out has remained virtually unexplored. I argue that whereas the above-mentioned forms of knowledge did not play a role in Ottoman Yemen, knowing local society was nevertheless a crucial element of Ottoman notions of mastering this province: debates over what the “customs and dispositions” (‘adat ve emzice) of the local people were and into which governmental practices they should be translated were central to the struggles over policy-making toward Yemen. Ottoman officials resembled European colonial rulers of the time in arguing that local society could be controlled effectively through the use of “accurate” knowledge about their “essential qualities.” Yet, in contrast to what occurred in parts of the British and Russian empires, Ottoman efforts at knowledge production in Yemen were not carried out by scholars-cum-administrators within the frameworks of scholarly societies. Rather, memoranda authored by locals or government officials or their oral testimonies remained the principal conduits of producing knowledge about local society whereas gazetteers or detailed ethnographic studies were the exception. These memoranda remained largely concerned with identifying social groups (e.g. descendants of the Prophet Muhammad) that could be co-opted for the purpose of maintaining Ottoman rule at the local level. While scholars have shown that local actors manipulated categories of rule by “inventing” customs for the consumption of Ottoman bureaucrats, I demonstrate that administrators competed both with each and with local power figures over who “accurately” interpreted local culture. Looking at Ottoman knowledge production in Yemen adds to a growing literature on late Ottoman imperial governance and state building.