This study investigated the conditions under which consumer participatory corporate social responsibility (CSR) campaigns could be effective and focused on power as the key variable. Specifically, based on motivational intensity theory, the interaction effect between participation effort and power was examined on CSR attitude and participation intention. In addition, this study tested the mediated moderating effect of power through self-efficacy in order to examine the mechanism behind the interaction effect. Results of two experimental studies (Study 1 and Study 2) showed a significant the interaction effect of participation effort and power on participation intention. When the consumer's power was low, participation intention was lower for those in the high effort condition compared to those in the low effort condition. On the other hand, when power was high, there was no difference in participation intention according to the level of participation effort. This study has significance in that it reaffirms and furthermore expands the existing academic results and presents practical implications.