The purpose of this research was to explore if the differentiation of self has a role in predicting capacity for mentalization in female samples. The data was collected using The Reflective Functioning Questionnaire (RFQ) and The Differentiation of Self Inventory (DSI) on a sample of 105 female participants, aged 18-50 years (M = 30.61, SD = 8.09). Both models containing self-differentiation as predictors were significant. The first model that predicted certainty about mental states explains 32.1% of the variance (R² = .32, F(6,98) = 7.732, p = .000), with I position (β = .459, p = .000) and emotional cutoff (β = -.245, p = .024) as significant predictors. The second model that predicted uncertainty about mental states explains 40.4% of the variance (R² = .40, F(6,98) = 11.086, p = .000), with age (β = .233, p = .007), education (β = -.208, p = .024), and emotional reactivity (β = .323, p = .005) as significant predictors. The obtained results indicate that different aspects of the differentiation of self can predict certainty and uncertainty about mental states in the female sample, but also that when it comes to phenomenon such as capacity for mentalization, certain sociodemographic variables (e.g., age, education) might play more important role then it was previously thought. Further research on this matter, with a bigger and more diverse sample, is strongly advised. Keywords: mentalization, self-differentiation, emotional reactivity, emotional cutoff