This study investigates when and how trait gratitude stimulates tourist citizenship behavior (TCB). Building on trait activation theory, the present study proposes a mediated moderation model in which tourists’ trait gratitude and positive resident–tourist contact jointly influence TCB. In driving TCB, the interactive effect of trait gratitude and positive contact is mediated by perceived insider status. Data were collected from 497 Mount Wuyi tourists and analyzed using structural equation modeling. The results reveal that trait gratitude positively influences TCB, and this relationship is moderated by positive contact. Furthermore, positive contact moderates the association between trait gratitude and perceived insider status. Additionally, perceived insider status, which is positively related to TCB, significantly mediates the moderating effects of positive contact on the link between tourists’ trait gratitude and TCB.