This study proposes a decomposition framework for quantifying contributions of the determinants of poverty to spatial differences or temporal changes in poverty. This framework is then applied to address the issue why poverty incidence is higher in inland than in coastal China. The empirical application requires household or individual income observations which, generally speaking, are not available. Thus, a data-generation method developed by Shorrocks and Wan is introduced to construct such observations from grouped income data. It is found that inland China is poorer than coastal China, mainly due to lower efficiency in resource utilization rather than less endowment of resources. Also, trade became poverty-reducing in coastal China in the late 1990s but remained poverty-inducing in inland China. Policy implications are briefly discussed.