This paper is intended to appeal to personality psychologists and direct their attention towards the broad topic of positive emotions', an area that, in spite of its relevance, has been scarcely developed in recent literature. Some of the reasons for the imbalance between the study of negative emotions and the lack of interest in positive ones are presented, and the types of positive affect that have been studied are briefly reviewed. After mentioning five reasons why personality psychologists should seriously consider the study of positive emotions, the paper focuses on both the causes and the consequences which positive affect has on several psychological processes. Since affect has been explicitly included in factorial models, the description and some of the explanations for individual differences in average levels of mood are presented. Links between affect and personality are examined through top-down, bottom-up, and interactive models. Finally, while considerations about the adaptive functions of emotions have made authors predict a generally negative quality of life for most people , many data show that feelings of well-being are prevalent. A final discussion includes a reference to Taylor's argument which asserts that positive illusions' are related to mental health.