Social media has become an essential channel for customer service. On the one hand, it provides great opportunities for firms to directly engage with customers and to publicly resolve problems. On the other hand, the publicity puts firms under unexpected risks when firms fail to address customer concerns adequately. In this paper, we first analyze firms’ adoption of Twitter and social media customer service (SMCS) through a two-stage model. We identify that corporate peer influence and consumer voices are the two key drivers in firms’ decision-making. We then examine how consumer complaining behavior evolves in response to firms’ service strategy.