Psychopathology is a science of methods in psychiatry for evaluation of abnormal mental states and mental disorders based on psychic alterations. Different methodological approaches have been used to enlight the phenomenology, pathogenesis, significance and nosological position of psychiatric disorders resulting in an enormous amount of knowledge concerning explanation and understanding of mental disorders. But the more the monstrous contemporary classification systems, e.g. ICD-10 and DSM-IV gained importance in the last decades, the smaller the interest in accurate phenomenological and psychopathological analyses and knowledge became. The main requirement for diagnostics and classification systems is its clinical relevance with respect to treatment and prognosis. Various empirical studies showed that classical categorical classification systems of mental disorders were of minor value concerning pathogenesis-oriented treatment approaches. A possible alternative to the classical categorical approach may be a dimensional approach. Such diagnostics focus on the constellation of conditions of single psychopathological phenomena and/or symptoms and its meaning for the patient suffering from them. According to the results of recent phenomenological and psychopathological studies the pathogenesis of a mental disorder has to be considered as a multidimensional process in which various mental, physical and social factors and their meanings for the sufferer act as predisposing, triggering, and disorder-prolonging factors. Effective treatment strategies have to be based on an accurate differential diagnosis concerning the complex constellation of conditions underlying and establishing the dynamic process of a disorder and its meaning