The importance of stirred media mills in various industries and in research is steadily increasing. The comminution process in these mills is determined mainly by the number of stress events in the grinding chamber and by the intensity acting at these stress events: for a certain stress intensity a certain relation between the product fineness and the number of stress events exists. Since the product of stress number and stress intensity is a measure for the specific energy, for each stress intensity also a certain relation between product fineness and specific energy exists. At similar stress intensities the influence of stirrer and grinding chamber geometry is small. Moreover, the influence of residence time distribution and mill geometry on the product particle size distribution, wear and process models are discussed.