This article examines the role of social reporting in the relationship between corporate social performance (CSP) and corporate reputation, as well as the differences in the roles between mandatory and voluntary social reporting.An analysis of Chinese listed firms separate social reports during 2006-2009 reveals a positive impact of social reporting on CSP-reputation relationship.More importantly, our findings further indicate that the positive relationship between CSP and corporate reputation appears stronger in firms voluntarily disclosing their social reports than those with mandatory social disclosure.This study also extends the CSP-reputation literature by providing an information asymmetry perspective with empirical evidence, rather than a traditional stakeholder or legitimacy perspective on social reporting.