This paper deals with the management of material groups at the purchasing department of "TGW Mechanics GmbH". After introducing the company itself, the fundamental principles of the material group management are presented. Subsequently various scopes of action are set, in which the development of material groups can be positively influenced. A close up is given on the topics market research, supplier / cooperation management and cost management. Based on professional literature research each topic has been analysed. Subject of the investigation is the identification of proper methods and tools to continuously improve the performance of specific material groups. An empirical study concerning market research and supplier / cooperation management has been conducted. Thereby a valuable insight into the practical work has been created. Furthermore, the information gained through guideline-based interviews has allowed a comparison between common practice and theory. Besides that, theoretical approaches have been adapted and customized. By merging them with the current management of material groups, recommendations have been elaborated pursuing the goal of making the purchasing at TGW even more efficient.