Abstract Trait forgivingness is the disposition to forgive interpersonal transgressions over time and across situations. We define forgiveness as the replacement of negative unforgiving emotions with positive, other-oriented emotions. Rumination has been suggested as a mediator between forgivingness and emotional outcomes; however, we suggest that different content of rumination leads to different outcomes after transgressions. In four studies of 179, 233, 80, and 66 undergraduate students, trait forgivingness was negatively correlated with trait anger, hostility, neuroticism, fear, and vengeful rumination and was positively correlated with agreeableness, extraversion, and trait empathy. The disposition to ruminate vengefully mediated the relationship between trait forgivingness and (1) anger-related traits and (2) both revenge motivations and state anger following a specific recent transgression, but it did not mediate between forgivingness and (1) fearfulness and (2) avoidance motivations following a specific transgression. Self-hate statements, a proxy for depressive rumination, mediated the relationship between forgivingness and both depression and fearfulness but not the relationship between forgivingness and trait anger. Future research should distinguish the contents of mental rumination following interpersonal transgressions.