Şimşek, Ömer Faruk (Arel Author)Personal sense of uniqueness, a major construct in humanistic psychology, has been recently shown to be a robust correlate of happiness. Yet the antecedents of this experience are not known. To address this limitation, we focused on extraversion and openness to experience, the two traits referred to as plasticity in higher-order framework of personality, as predictors of uniqueness and happiness. In light of theory and past empirical research, we proposed that the two traits representing plasticity would promote a sense of uniqueness, which in turn influence happiness. This model was tested in a college sample (N = 370) by relying on structural equation modeling. Results showed that uniqueness mediated the associations of extraversion and openness to experience with happiness. This model was supported when the effects of neuroticism, a marker of vulnerability to psychopathology, on uniqueness was taken into account. The implications of the findings for future research were addressed and sense of uniqueness as an element of a good life was highlighted