This study investigates whether firms are more active at corporate social responsibility when they are more connected to others. Based on social network theory and legitimacy theory, this paper hypothesizes that firms, which are centrally located in social networks, tend to be more active at corporate social responsibility. The association is expected to be stronger when firms have higher profitability, or lower book-to-market ratios. Also, the relationship is predicted to be stronger under the good macroeconomic environment. Empirical analyses show that firms’ social networks are positively related with corporate social responsibility activities. The relationship is found to be stronger for profitable firms and under good economic conditions. But this study could not find interaction effects for book-to-market ratio.