Sun, AonanWang, KunWu, YueZhu, Nathan Zhenghang2026-01-222026-01-220022-2186https://hdl.handle.net/1885/733804840Corporate social responsibility (CSR) reporting reforms are increasingly adopted worldwide, yet their implications for firm value and externalities remain unclear. Using a novel handcollected dataset of global CSR reporting reforms and a stacked difference-indifferences design, we find that treated firms experience a 9.25% decline in firm value but a 16.4% reduction in CO₂ and CO₂ equivalents emissions and a 10.27% increase in CSR ratings. Effects are stronger under reforms requiring greenhouse gas disclosures, lacking safe harbor provisions, not recommending a specific reporting framework, or not mandating external assurance. Stronger changes also emerge in jurisdictions with weaker stakeholder orientation and more developed market institutions, and among firms without CSR-contingent executive compensation and those with weaker CSR transparency and performance. At the country-level, reform jurisdictions reduce emissions by 40.75 million metric tons, yielding societal savings of $7.5 billion. Overall, CSR reporting reforms reduce firm value, but generate significant societal and environmental benefits.84en202510.2139/ssrn.5694483