Customer loyalty is an important building block for the success of companies. Accordingly, the scientific literature on this topic is extensive. However, aspects of loyalty between manufacturers and dealers in vertical contract marketing systems have so far been neglected. While contract dealers are "bound" dealers, inherent conflicts of interest within the system lead them to act against the interests of the manufacturers. Using the market for spare parts in the automotive industry, Klaus Bodensteiner defines the concept of customer or dealer loyalty and develops a causal-analytical model for its explanation and measurement. He empirically tests his findings and demonstrates implications for automobile manufacturers.