This paper considers the debate on common property resources by exploring the conditions under which rural communities in Southern Thailand implemented and enforced rules of restricted access in coastal fishing. Particular emphasis is placed on the ways in which socio-economic differentiation affects the willingness and ability to bear the costs of enforcing and maintaining rules of common property. Variations in status and wealth, it is argued, have a profound impact on the extent to which individuals at the lower end of the socioeconomic spectrum can participate in this important socio-political activity. Because they lacked the endowments that were essential for monitoring and enforcing the enclosed fishing area, poor villagers were effectively excluded from the act of “protecting” the village, an act that carried tremendous status within the village community. This paper is based on a case study on Phuket. Around the beginning of 1995, the village of Baan Ao Lom (a pseudonym) took the rather unusual decision to restrict its local fishery from vessels using trawlers, push nets, explosives and poison. According to village accounts, access was open to any vessel that agreed to refrain from using the banned technologies. Enforcement of the CPR was exclusively dependent upon collective action from within the village community. The principal means that villagers used to enforce the ban were intimidation and deterrence. Thus, the CPR that emerged in Baan Ao Lom was remarkable for its near total lack of formal or written, pre-determined rules regulating the ways in which individuals entered, exploited and protected the fishery. A principal aim of this paper was to consider the ways in which environmental scarcities affect collective action and institutional change. The findings from Phuket provide evidence to support the notion that resource-dependent communities can institute and enforce rules of common property. In addition, they suggest a relatively strong correlation between environmental degradation and institutional change.