In recent years the way in which problems are approached in the assembly area within the manufacturing firm has gained increasing importance for economic planning. In connection with this, the demand for long term economic flexibility of assembly systems comes to the forefront. A firm should not limit itself purely to investment decisions in the planning of assembly systems, if it is to successfully meet growing demand (on both the market and technology fronts). However, it has become essential even in this field that strategic thinking and planning are considered more important than they have been in the past.There are considerable difficulties, however, associated with the strategic decision-making processes involved in the planning of flexible assembly systems. System Dynamics assembly models are currently being developed at the Business Management Institute at Stuttgart University ( within the framework of the “Sondereforchungsbereich 158” sponsored by the DFG).The aim of this is to understand and cope with these problems more easily, with specific reference to long-term decisions, the lacking objective assessment criteria and the high complexity of the problem.