This study was performed to understand the customers' motivation to voluntarily engage in value co-creation behaviors from the perspective of psychological ownership and customer engagement. An online survey on eight leading smart phone FB fan pages was employed to test the hypotheses derived from the research model. Results indicated that customers with high psychological ownership of brand tend to voluntarily provide feedback, become advocates for the product among their peers, and help other customers. At the same time, highly-engaged customers are likely to disseminate positive information and recommend product to their friends, assist other customers to solve problems, and remain patient under service failures. In addition, feelings of psychological ownership and customer engagement are enhanced by customers’ self-concept and self-investment. We draw on these findings to offer implications for researchers and practitioners.