We examine the relationship between corporate social responsibility (CSR) and credit risk. We test how CSR strengths and concerns impact credit default swap (CDS) spreads during the global financial crisis period (2008?2009) and non-crisis periods (2001?2007 and 2010?2011). We empirically find that CDS spreads capture additional effect of CSR on credit risk that credit ratings miss, implying that CDS spreads have advantages over credit ratings for studying CSR. Our empirical results show the asymmetric effects of CSR concerns and strengths on credit risk. CSR concerns increase and CSR strengths reduce CDS spreads during the non-crisis period, whereas their effects change during the financial crisis. CSR strengths during an adverse economic environment can indicate agency problems and overinvestment. The effect of CSR concerns becomes much larger during the financial crisis, while that of CSR strengths can even increase CDS spreads. These results are supported by a 2SLS analysis used to mitigate endogeneity problems.