Alexithymia, a personality trait characterized by difficulties identifying and describing feelings and an externally oriented thinking style, is associated with negative moods such as depression and anxiety. The present study examined fears of positive moods (happiness and compassion) as potential mediators of this relationship. A nonclinical online sample of 206 male and female young adults completed validated measures of alexithymia, fear of happiness, fear of compassion, and negative moods (depression, anxiety, stress). Alexithymia was positively correlated with fear of happiness, fear of compassion, and negative moods. A hierarchical regression model with alexithymia and fears of positive emotions as predictors, controlling for demographic variables and socially desirable responding, explained 64% of variance in negative moods. Mediation modelling that controlled for demographic variables and socially desirable responding indicated that fears of happiness and compassion were partial mediators of the association of alexithymia with negative moods, with the indirect effects predominating over the direct effect. Results are discussed in terms of previous research and theory as well as potential clinical implications for addressing the reported relationships of alexithymia, fears of positive emotions, and negative moods.