Purpose - The purpose of this master thesis is to investigate the possibilities to extend or change the base of IKEA’s SL classification and give recommendations concerning potential improvements.  Method - This thesis has an inductive research strategy since data has been collected to build theory rather than the other way around (Bryman and Bell, 2007). The data has been collected by qualitative research, mainly through interviews with employees at the different IKEA organisations. Empirics - The empirical data gathered describes the service level in practice at IKEA. In order to get an overview of the conflicting interests in the different functions, the chapter is divided into four themes; how IKEA works with SL, the purpose of SL, customer service and suggestion to the design of the SL classification. Theory - The theory has been based on our empirical findings in order to find the best solution for IKEA. The theory includes different classification models, the relationship between customer service and SL and is finished with a section on how to measure availability. Conclusions - The conclusion that could be drawn was that the purpose of the classification was not perceived in the same way within the company and that both internal and external information is needed. A new model is presented that takes into account the different products, buying situations, and customer reactions on OOS, which are important parameters for consumer perception of availability and customer service. By using this model IKEA will be able to fulfil the two, sometimes conflicting purposes; to secure the sales and increase customer satisfaction.