Self-efficacy, optimism and social support have been consistently related to health and functioning. In this study a specific hypothesis was tested: self-efficacy expectations, as a representation of a capable self, and perceived social support, as a representation of a helpful world, shape optimism which is an outcome expectation. Optimism in turn predicts satisfaction with life and depressive symptoms. Satisfaction with life and depressive symptomatology both served as indicators of well-being. Two hundred and one (201) individuals participated in our study (average age 41.57 years). The hypothesis was tested through Structural Equation Modeling. Six different models with optimism, self-efficacy and social support as possible mediators were consecutively tested and compared. According to only model that provided fit to the data, optimism partially mediates the relation of self-efficacy and perceived social support to well-being. Optimism was predicted by daily emotional support and self-efficacy.