The scholarly work on China's environmental regulations in the context of “central–local” relations is dominated by the preference for a centralized approach. This article examines a centrally imposed and executed verification programme of locally reported pollution data, a rare and sustained central effort to enforce an environmental policy, namely the national pollution reduction target system. The programme was established in 2007 to curtail perceived widespread data falsification and to enhance the quality of emission data, the basis for assessing local compliance with targets. Based on an analysis of official documents and interviews with environmental officials and industry representatives, this article found that the verification programme appears to have reduced the overreporting problem with emission data, enhanced local monitoring and enforcement capacity, and to a certain degree deterred violations due to the increased frequency of national and local inspections. Nevertheless, significant challenges remain. Verification is highly resource intensive, it has involved little external oversight and public participation, the central authority has exerted significant yet unchecked discretionary powers, and poor data quality has remained an issue. Over time, the verification programme appears to have turned into essentially a “numbers game.” All those challenges indicate that a centralized enforcement approach is arguably ineffective in addressing China's long-standing problem of weak environmental policy implementation. This study also sheds lights on the classical “principal-agent” theory in the study of public bureaucracy. Not only does the principal distrust the agent, which is the main concern of the theory, but the agent also distrusts the principal.