In 2009, the Institute of Public & Environmental Affairs (IPE) and the Natural Resources Defense Council (NRDC) jointly developed the Pollution Information Transparency Index (PITI) to establish a baseline for the first year of China’s environmental information disclosure and to record every step of the country’s information transparency. The Measures for Environmental Information Disclosure (Trial) have now been implemented for nine years, and eight rounds of the PITI evaluation have been conducted. While reviewing PITI reports over the years, one can observe the subtle trajectory of change and analyze the motivations behind progress. Over eight PITI reports, we observed the quantity, quality, frequency, and user-friendliness of pollution supervision information disclosure. Most gratifying of all, we observed the solid foundation of environmental legislation and policy development behind these trends.