With growing concerns about the dark side of social networking sties (SNSs), IS scholars pioneering technology addiction have begun to advocate for more MIS research to better conceptualize and examine problems related to technology use. In this study, we adopted the cognitive bias perspective to explain how SNS addiction distorts users' cognition and affects their decision to continue using SNSs. We tested our research model with 238 active Facebook users and the results support our research model and hypotheses. Specifically, we found that Facebook addiction influences the usage decisions by altering user belief systems (i.e., intensifying their cognition about how Facebook use fulfils their needs). We expect that the findings enrich the literature on IS use by confirming the role of addiction in IS usage decision in the context of SNSs. We also believe that the findings provide SNS service providers, educators, and parents with some insights into the impact of SNS addiction.