Objectives : The main objective of this study was to support the existence of emotional dimensions common to anxiety and depressive symptomatology, and confirm the common elements of emotional vulnerability, characterized by negative affectivity and alexithymia operation. The second objective of this study was the identification of characteristics specific to each disorder. We made three assumptions:1) there is a significant relationship between anxiety and depressive symptoms, 2) exists on community processes between these two entities, objectified by the sub dimensions of negative affectivity and the difficulty in identifying emotions 3) certain dimensions are specific to each disorder. Method : The study participants were students from 1st to 4th year of the University of Provence. The sample consisted of 317 subjects (77% female and 23% G; mean age = 20, 61 ± 1.55), who gave written informed consent and completed questionnaires collectively. We administered to the subjects a protocol consisting of three self-assessment scales to assess emotional dimensions and anxiety and depressive symptomatology. The dimensions of affectivity were assessed by the EPN-31. It consists of 31 items grouped into three factors: positive emotions, negative emotions and feelings of surprise. The emotional functioning was assessed by the scale of the Toronto alexithymia (TAS-20). It allows an overall assessment of the level of alexithymia, as well as three dimensions as represented by specific sub scales: difficulty identifying emotions (DIE), the difficulty to differentiate emotions (DDE), and thought oriented l outside (PEO). This scale is most used in the assessment of alexithymia. The anxiety and depressive symptoms was assessed by the subscale of anxiety and depression of the SCL90-R. This scale is widely used in screening for psychiatric symptoms, and has been validated internationally. Statistical analysis: we performed descriptive analysis, correlational analysis (correlation of Bravais-Pearson) and hierarchical multiple regression with SPSS 15. Results validate our assumptions. We observe significant correlations between anxiety and depressive symptomatology and vulnerability factors (negative affectivity, emotional activation and alexithymia). The proposed model can retain common elements and specific dimensions operating respectively for anxiety and depression. Discussion : Our study reveals the existence of a "common nucleus of vulnerability characterized by negative affectivity associated with difficulty identifying emotions. Specific dimensions appear nevertheless exist, and depression is strongly explained by low positive affect (anhedonia dimension); anxiety associated specificially to emotional activation and finally thought outward, marking the size limitation the imaginary life in alexithymia, appears to operate in depression, perhaps as a mechanism of emotional repression. The involvement of alexithymia in the functioning of the affective disorder is confirmed, this helps to clarify the modalities of therapeutic care that we offer.