This paper focuses on the changing political context for the resolution of transboundary environmental problems involving Hong Kong and the neighbouring Pearl River Delta Region (PRDR) of Guangdong Province, People's Republic of China. Awareness of possible transboundary movements of pollutants between the Mainland and the former UK colony initially developed in the years prior to reunification in 1997. Since 1997, however, there has been increasing concern in the Hong Kong Special Administrative Region about transboundary pollution resulting from rapid urbanization and industrialization taking place in the PRDR. Only now are studies under way to gain a deeper understanding of the nature and causes of these problems. Little progress has yet been made to put in place suitable institutional structures and related environmental planning and management approaches through which to tackle them. The paper examines the problems and dilemmas raised by transboundary pollution between Guangdong Province and Hong Kong, the need to develop appropriate models, policies and institutional structures to handle such issues, and the longer-term prospects for sustainable development in the PRDR.