The purpose of this study is to determine what constitutes effective corporate social responsibility (CSR) communication in the corporate blog setting. This study examines the effects of a company's prior reputation and blog responsiveness on public perception of CSR motives, attitudes, and intention to engage in word-of-mouth (WOM) communication. The results show that prior company reputation has a strong effect on the public's interpretation of CSR motives, their attitudes towards the company, and their intentions to engage in WOM communication, while blog responsiveness influences the public's attitudes towards and perception of CSR motives. The interaction effect between prior reputation and blog responsiveness on WOM communication was confirmed, meaning that for a company with a negative reputation, responsiveness is critical when communicating CSR practices. We suggest that responding to the public's comments or questions about a company's CSR activities may convince them about the company's sincere motives whereas no response engenders suspicion toward a company's motives.