Differentiating normal and abnormal personality is a problem in clinical practice. The use of distinct categories, as for example in DSM-IV-TR (APA, 2000), is always difficult due to the fact that underlying dimensions are similar for psychopathology and normality. Moreover, it is impossible to have only one unique theoretical definition since each approach highlights different aspects in its vision on normality and abnormality. Therefore, categorical and dimensional perspectives and psychodynamic, interpersonal, cognitive, psychobiological, evolutionary and five-factor approaches are explored. The different approaches do agree on some features of abnormal personality: inflexibility, inadaptability, rigidity, imbalance and unadjusted intensity. However, each personality style, normal or abnormal, will have some adjusted and some unadjusted features. Hence, it is probably less essential to define an exact boundary between normality an abnormality, than to focus therapy on attaining optimal functioning, taking the personal situation into account.