Despite abundant research on emotions, the more complex features of emotional experience, such as mixed emotions, have only been recently investigated. The present research project presents evidence from five studies dedicated to better understanding the origin and consequences of mixed emotions (i.e., the co-occurrence of oppositely valenced emotions, such as feeling happy and sad). Firstly, a meta-analytic review of the literature (k=63) determined mixed emotions as a robust and a non-artifactual experience. Study 1 (N=35) showed that goal conflict significantly predicted greater levels of mixed emotions compared to when no conflict was present. In Study 2 (N=57) actual goal conflict experiences predicted greater levels of mixed emotions compared to another intergoal dynamic (i.e., facilitating goals). Findings of Study 3 (N=429) supported the relationship between goal conflict and mixed emotions using a cross-sectional design, and confirmed a positive correlation between mixed emotions and different measures of eudaimonic well-being. Results of Study 4 (N=52) demonstrated that eliciting mixed emotions in a sample of students about to graduate produced greater levels of eudaimonic well-being. Finally, Study 5 (N=73) used an experience-sampling design to clarify the association between mixed emotions and eudaimonic well-being such that: (1) individual differences in mixed emotions interacted with goal conflict to predict greater levels of life-purpose; (2) fluctuations in mixed emotions mediated the relationship between goal conflict and efforts to resist temptations, (3) mixed emotions also interacted with efforts to resist temptations, which was associated with enhanced vitality. The findings of these five studies are integrated and discussed in terms of their implications for goal theory, well-being related outcomes and emotional complexity theory. Overall, this research project's main contributions are: that goal conflict is a prominent predictor of mixed emotions, and that mixed emotions can help people to overcome the negative consequences of goal conflict, enhancing eudaimonic well-being.