This dissertation investigates how rural women and men in Tanzania's Iringa Region access and stake claims to land in a context of agrarian commercialization and liberal reforms to land law and administration. The study is based on 11 months of research in highland villages that have experienced a boom in commercial forestry, rapid land-buying, and increasing rates of land-related disputes. These trends have been accompanied by widening use of written contracts and title deeds, and increasing recourse to state courts to adjudicate disputes. Based on ethnographic, interview, archival, and participatory methods, this study examines how various land claimants combined material, documentary, and social practices in order to claim rights to land, as well as to social entitlements linked to landholding. Drawing on processual approaches to law and property in post-colonial settings, this research analyzes how property rights, broadly conceived, are established and remade through articulations between legal processes and rural social relations structured by kinship, gender, and class. The overarching argument of the dissertation is that growing markets and increasing formalization of land-claiming in Iringa have not eliminated other, “customary” modes of defining and regulating rights. Neither have they detached rights from local forms of kinship, autochthony, and political allegiance. Instead, modernist techniques for administering land rights function by articulating with these place-based and extra-legal relations. The dissertation elaborates this broad contention across three more specific arguments. First, it shows that formalization techniques become efficacious for advancing claims precisely when they articulate with claimants’ local knowledge and with everyday norms of status, duty, and reciprocity. Legal systems of property rights are thus shaped by social relations that they exclude from view. Second, the dissertation argues that the heightened social inequalities that accompanied formal governance resulted not from direct legal-institutional exclusion, but rather from by increasing the material, symbolic, and social resources that rural actors needed to mobilize in order to have their rights recognized. Formalization thus advantage rural elites who were positioned to mediate others’ access to legal processes. Meanwhile, women and other subaltern claimants’ weaker command of these resources led them to instead rely on kinship-based mechanisms of access. Yet, despite their disadvantages, these groups also invoked statutory principles and engaged with state courts in pursuit of more secure rights. Finally, the study contributes to studies of contemporary agrarian change in Africa by arguing that their pluralistic constitution means that property regimes in changing agrarian settings are highly social and geographically variegated. While formalization is often understood as a homogenizing technique, its operations in Iringa proliferated the means of pursuing land-claims and heightened uncertainties about legal status. By revealing how the construction of legal property is enduringly shaped by intersecting, place-based relations, this study opens critical questions concerning the trajectories of property formation, social differentiation, and agrarian development across Africa’s agrarian landscapes.