The marketing environment has changed significantly in the past decade, such as globalization, increasingly fierce competition, technology development, and so forth. Today’s customers have more expectation in shopping experience and wish to interact with suppliers closely. They have more choices and their demands often change quickly. The old marketing approach, one to mass marketing, is not suitable to the changing environment. The one to one marketing approach is the trend for companies to achieve sustainable competitive advantage against competitors. For many industries and companies, their most profits come from a small number of loyal and profitable customers. The Pareto rule suggests that 80% of profits are generated by 20% of customers. Therefore, how to understand customers and keep the profitable customers is the key task for companies. Relationship marketing and customer relationship management systems (CRMs) will help companies achieve those objectives. Currently, more and more companies implement CRM system, however, many of them don’t achieve the expected performance or even failed. One of the main reasons is that those companies just regard CRM project as technological project or marketing project rather than consider it to be a whole organization change and long-term strategy. Actually, when implementing the CRM system, companies should consider many critical success factors with a holistic view, such as organizational structure, corporate culture, reward system, training system, and so forth. This study is to explore what critical success factors affect the success of CRM implementation and how companies integrate these CSFs to facilitate the implementation.