["Scandinavian Journal of Psychology, EarlyView. ", "\nABSTRACT\nMind wandering frequently entails affective content, and the affective valence of such thoughts is closely related to individuals' mood. However, the neural mechanisms underlying this relationship remain unclear. Using an individual differences approach, the present study examined whether the affective valence of mind wandering is associated with resting‐state functional connectivity among brain regions commonly implicated in mind wandering, and whether it mediates the relationship between such connectivity and mood. Resting‐state functional magnetic resonance imaging (rs‐fMRI) data were acquired from 92 participants, who subsequently completed an experience‐sampling film‐viewing task to assess mind wandering, its affective valence, and mood. Behavioral results showed that more positively valenced mind wandering was strongly associated with more positive mood. Neuroimaging analyses revealed that the affective valence of mind wandering was positively associated with functional connectivity between the right rostromedial prefrontal cortex (rmPFC) and the left inferior parietal lobule (IPL). Mediation analyses demonstrated that the affective valence of mind wandering mediated the association between this functional connectivity and mood. These findings may support the content regulation hypothesis and the dynamic framework of spontaneous thought.\n"]