A warehouse management system (WMS) has the task of controlling, monitoring, and optimizing warehouse and distribution systems. Although the logistics and process know-how is a major success factor for WMS providers, there is often a lack of common understanding with customers. In this context, problems in WMS implementation are often due to their low process knowledge. For this reason, the present work pursues the goal of developing a reference model of a Warehouse Management System. This reference model should clearly represent the essential logistic core processes for different contact persons of a customer with different process know-how. Based on a literature research, a reference model framework (reference model overview) is defined in this context. The modeling of the structure of the reference model is subsequently based on the processes of a specific WMS, the findings from theory and a representative reference warehouse (manually operated distribution warehouse). Based on the reference model framework (division into management, support and core processes), the resulting reference model consists of three levels. The first level represents an overview of the main warehouse processes (core processes and support process of “relocation of stocks”). A further concretization follows on the logistic level, which shows the processes from the point of view of a warehouse staff without going into more detail about the internal behavior of the WMS. In contrast, the technical level shows an interaction between warehouse personnel and WMS. However, the structure of this last level is only shown by an example process.