The purpose of this Masters thesis is to compare the scheme structure of two national classifications system, namely the Swedish SAB system and the German ASB. It has been assumed that there are no major differences between the two models of classification systems or the main classes into which documents are placed. The classification theory and subject analysis, which form the basic theory on which my research is based, are taken from Dahlberg, Langridge and Rowley. A comparison of 30 monographs classified in the SAB system Sveriges allmänna biblioteksförening and in the German ASB system Allgemeine Systematik für öffentliche Bibliotheken showed that the classification structure was primarily responsible for determining where a particular document was placed. However, despite the fact that the subject in various documents may be similar, my research will demonstrate that the structure of the two codes also depends on different interpretations of the main subject in a document. My conclusion is that is not only the model of the classification system that determines the result of a classification, but also the extent of previous knowledge and the depth of interest for the subject being classified, held by the classifier.