Research indicates that forgiveness of interpersonal transgressions relates to better sleep quality, whereas maintaining feelings of anger and hostility relates to poorer sleep quality. However, the mechanisms explaining these relationships have yet to be determined. We examined whether negative affect and anger rumination mediate the relationship between forgiveness of others and sleep quality using a sample of 277 undergraduates from a medium-sized Midwestern Catholic university. Participants completed self-report questionnaires assessing forgiveness of others (situational and dispositional), sleep quality (nocturnal sleep and daytime fatigue), negative affect (depression and anxiety), and anger rumination. Using structural equation modeling, we found that negative affect and anger rumination mediated the relationship between forgiveness and sleep quality through two indirect pathways. In one pathway, negative affect mediated between forgiveness and sleep quality. In the second pathway, both negative affect and anger rumination functioned as mediators. Implications for clinicians and researchers are discussed.