Nowadays, Customer Relationship Management (CRM) has been a competitive edge of many companies. It is critical for companies to get and maintain profitable customers. For the purpose of sustaining this competitive edge, companies should manage the Customer Information (CI) more effectively The major goais of this research are 1) to identify the activities of the Customer Information Management (CIM) and the factors influencing on the CIM, 2) to show the relationship between the proficiency of the CIM and the CI Quality, and 3) to verify the mediating effects of the proficiency of the CIM Process between the influencing factors and the CI Quality. An empirical study was undertaken to test the hypotheses with data from 65 companies. Multiple regression analysis and ANOVA were employed to test the hypotheses. We found that 1) there are 6 activities in the CIM process and 5 factors affecting the CIM, 2) the proficiency of the CIM process is closely related to the CI Quality, and 3) the proficiency of the CIM process plays the mediator between the influencing factors and the CI Quality.