Implicit in any urban design is a negotiation between public and private interests. Such a negotiation is articulated and made legible in the facades, fences and even more subtle edges separating this from that. A complex variety of spatial situations are produced depending on how spaces are framed, how interfaces are materialized. In the city, the interplay of open space, building and boundary produces a patchwork of subspaces, which we can consider as potential urban territories. Most of us are familiar with the results of territorial production and recognize that fences, furniture or plantings are claims to space by an individual or group. However, the reason to conceive of this process as a territorial production may not be immediately apparent. Consequences of territorial production on percep-tions and behavior are rather under-analyzed, especially in the context of the city. This thesis looks specifically at territorial responses to urban form in the potential social arenas of shared yards in multifamily housing schemes. Drawing on territoriality- and commons-theory as a basis for morphological studies using spatial analysis (e.g. GIS), the thesis proposes that territorial uses of space are in part connected to characteristics of urban form. The thesis explores these spatial underpinnings of claims on space, examining historical, sociological and architectural perspectives and implications on current planning praxis. Parallels are drawn with the role of excludability and rivalry in the production of goods as per commons-theory. Recognizing that even territories like yards perform differently depending on built form characteristics is a step to designing open space with greater social utility. Most notably, the findings that spatial enclosure supports sense of ownership while spaciousness and size support frequency of use is knowledge useful to the practitioner with a role in the production of urban environments, whether in planning, design or construction. With increasing focus on sustainability in urbanism, factoring in social sustainability in land use means recognizing what makes yards inviting to use and elicit feelings of stewardship. Moreover, the importance of legibility at the interface of public and private has implications for design of public space as well. What appears to have been insufficiently problematized in the past are the non-excludable, rivalrous yards which appear to be parks, but do not perform as such territorially. The thesis suggests how a theoretical basis may support design inter-ventions and even densification to resolve such “territorial instability.”