Among the upland Ibaloi of the northern Philippines, political and economic integration into the Philippine state has been informed by simplistic notions of local pattems of resource control and use. The view that minority tribal groups are 'communal', and the subsequent state efforts to privatize resource control, have resulted in the emergence of multiple levels of property rights. These, in turn, are manipulated by individuals in their economic strategies, a process which enhances and reinforces legal pluralism. The result has been to reduce agricultural productivity and to increase the level of conflict among community members. This article discusses the Ibaloi example to demonstrate the importance of re-examining our key concepts and approaches to property systems, in order to encompass factors of both structure and process. From September 1983 to August 1984 I was involved in a study of the social organization, productive technology and property system of the Ibaloi of northern Luzon, in the Philippines. The study was conducted in Kabayan, a community of wet-rice cultivators in the Agno River valley. The Ibaloi are one of many upland minority groups in the Cordillera Central who are being drawn into the national political and economic sphere. The study had two broad goals. The first, practical goal was to understand the social context of upland irrigation and the implications of that context for rural development planning. The second, theoretical goal was to gain insight into the group control of productive resources in a cognatic society. This article discusses several conclusions drawn from the research which together challenge a tendency to oversimplify non-Westem property systems in anthropological theory. This tendency results from several factors, including a piecemeal approach to the study of property systems, an overemphasis on synchronic data and the underestimation of the impact of plural jural systems in most modem societies. I show that this kind of oversimplification has also informed bureaucratic decisions which, in turn, undermine indigenous production systems among groups such as the Ibaloi. Drawing on the Ibaloi example, I emphasise the importance of demystifying property systems in non-Western societies. Several interrelated topics are addressed, namely: local group control of productive resources, especially in cognatic societies; the impact of political incorporation and economic integration on such control, especially in terms of legal pluralism; and the implications of the above for development planning, especially in irrigation. I conclude by arguing that, as in other areas of anthropology, our analysis of property systems must be informed by concepts both of structure and of process; our methodologies must