["American Journal of Economics and Sociology, Volume 80, Issue 2, Page 503-547, March 2021. ", "\nAbstract\nThe debate on the vitality of the commons remains unsettled, but the attempt by the Chinese state to develop a marketized property rights system to address the so‐called tragedy of the commons has backfired. In Shanghai and other major Chinese cities, the economic transformation has led to an ambiguous property rights system that creates complex and uncertain property relations between the state and private land developers. The resulting ineffective uses and conflicts in the commons are well known, but how to address them is contested. Can privatization drive better use of urban land in China? How do the ambiguous property relations between the state and the private sector affect the spatial design, management, use, and quality of the urban commons in Chinese cities? This article addresses these questions by engaging theoretical debates on how the commons should be held, analyzing the origin and key features of the ambiguous property relation in China, and drawing on a property rights approach to investigate the empirical case of a specific privately owned and managed urban park in Shanghai. The results show that not only does the commodification of property create inherently pervasive ambiguity in the land market, marketization also denies citizens their rights to public space. These findings raise fundamental questions about the idea that marketizing land is a sure tonic to address social problems. The article puts the case for reconsidering the institutionalization of the urban commons.\n"]