Diagnostics comprise a central, characteristic and defining professional activity for most psychiatrists. The starting points of the psychiatric curriculum have as a consequence, that the importance of a systematic training in and study of the diagnostic process tends to be underscored. A course of diagnostics is proposed and described, starting from the view that psychiatric diagnostics could be described as a process of increasing reduction and interpretation and as a translation of the experiences and behaviour of the patient in the language of psychiatry. A model is presented to carry out this course firstly by presenting the phases of the diagnostic process with daily practice as a starting point, secondly by discussing the possibilities and boundaries of supplementing and validating the original examination and thirdly by discussing diagnostics from a theoretical point of view.