The aim of this study was to assess the mediating role of affects between mind-wandering and happiness. The study was conducted with a sample comprising 270 university students—133 men (49.26%) and 137 women (50.74%)—who filled out the Mind-Wandering Questionnaire (MWQ), the Positive and Negative Affect Questionnaire (PANAS), and the SHS subjective happiness scale. Mind-wandering was found to be negatively correlated with happiness and positive effects. Higher mind-wandering-related scores went hand in hand with scores related to both lower happiness and positive affects. Approximately half the participants yielded low mind-wandering and negative affect scores and above-average happiness and positive affects scores. In addition, one in four scored above average in terms of mind-wandering and low in terms of happiness and positive effects. Finally, the mediating role played by affects was examined. It can be concluded that although in principle mind-wandering has no direct effect on happiness, some influence can be attested when affects, both positive and negative, are taken into consideration.