Time bank known as “Community/Neighborhood Pension”, provides a new solution to fulfill the unmet service needs of community members with idle community resources. The operation of time banks relies on the active participation of community members. Therefore, in this study we investigate the motivation of members to participate in web-based time banks from a service requirement narrative perspective. Drawing on grounded theory and self-determination theory, we built a model to assess how intrinsic and extrinsic cues underlying service requirement narratives affect time bank participation decisions of service providers. To test our hypotheses, we conducted a regression analysis of 12339 projects from the “Nansha Time Bank” (a web-based time bank) platform in China. We find that participants respond positively to time coin returns and narratives highlighting social connection and value fulfillment but respond negatively to service hour costs and empathy-altruism cues.