Social media that allow users to share, create, discuss, and exchange user-generated contents have opened up the potential for co-creation. However, because of social media's the nature of ubiquitous connectivity, customers are involved in a short-term relationship in which customers can choose to interact with multiple firms and switch one firm to another with relatively little effort and cost. Although an increasing number of firms have recognized the advantages of customer participation, it is difficult for firms to engage customers with their co-creation activities. To address this issue, this research integrates the theories of person-environment fit and task-technology fit to propose a research framework that helps understand how fit play an important role in customer participation, which in turn leads to favorable outcomes. A Web-based survey is conducted in Facebook to validate the proposed framework. The current research is expected to contribute to the theories by examining the theories of person-environment fit and task-technology fit in the context of co-creation. The current research is also expected to contribute to the practices by illustrating that firms could attract and motivate customers to participate by harnessing customer identifications, offering incentives, deploying various functions of social media technology.