In retail stores, handling of products typically forms the largest share of the operational costs. The handling activities are mainly driven by the shelf stacking process. While the impact of the handling costs on the profitability of a store is substantial, there are no models available of the different drivers influencing store handling. In this paper, a study of the shelf stacking process is presented. First, a conceptual model based on warehouse operations is derived. It is shown that stacking costs are non-linear with the number of consumer units stacked. Secondly, by means of a motion and time study, data has been collected for dry groceries in four stores of two different European retail companies. Using regression, the developed model clearly demonstrates the impact of the most important drivers for stacking efficiency: case pack (CP) size, number of CPs stacked simultaneously, the filling regime and the working place of the employees. Efficiency gains of 8–49% by changing the driver parameter value are identified. Based on the presented insights both retail companies have already decided to structurally change their current operations.