The present study analyzes C.E. Rusbult's investment model in the field of banks. Using two Italian samples, the model is tested with regard to geographical differences and the level of customers' trust in their bank. Results show that satisfaction is influenced by rewards and costs resulting from the relationship. Client-bank commitment is influenced by satisfaction and investments and negatively related to the intention to terminate the relationship with the bank. Differences between urban and provincial clients and especially between customers with low and high levels of trust in their bank were found.