Abstract: The present Master thesis broaches the issue of market segmentation and its importance for the Industry and Transportation department of 3M Česko. Market segmentation has been recognized to be a very important tool for strategic marketing planning but currently, its implementation at 3M in the Czech Republic is in an early stage and therefore rather unorganized and not yet framed by precise guidelines. The hypothesis is that linking together need-based and descriptive customer behavior characteristics would lead to more effective market segmentation within the 3M Industry and Transportation department. Therefore, the goal of this paper is to first of all test if the hypothesis is right and if so develop a segmentation method that combines descriptive as well as need-based segmentation criteria. It is to be shown that such an approach could improve segmentation efforts at 3M Česko and lead to more reliable results. The question that arises is whether 3M has understood the benefits market segmentation can bring for the company. And what has to be done in order to improve clustering of customers and to increase 3M's sales volume? Can segmentation take place on one level or is a multi-layer approach the better option? The present study tries to answer these questions by comparing theoretical findings from an extensive literature review with results obtained from semistructured interviews with 3M sales and marketing managers. Above all, one of the main points for improvement in the future is the collection of more market data and the combination of primary data with secondary information already available. The interviews have shown that even though managers are aware of the difficulty to understand 3M's complex and broad market, the feeling predominates that not enough effort is put into gathering additional information. Furthermore, it is recommended to perform descriptive segmentation through the usage of industry coding on a division-wide level, whereas need-based segmentation will be subject of each division individually. Moreover, keeping track of customer data in a standardized database is the key to success. The given recommendations are divided into actions that can be undertaken in the short, medium and long run in order to reach a department-wide effective and efficient use of the multi-layer segmentation in an organized and timely manner.