The enterprise resource planning(ERP) system becomes more popular as a vehicle of realizing an integrated information system, because this system not only facilitates the reengineering of processes in a firm but also provides the function of generating consolidated financial statements. However, ERP vendors have unsuccessfully provided methodologies on the customization of ERP packages although one of the important issues during the implementation of an ERP package is how to customize it. The purpose of this paper is to build a strategy on the successful customization of ERP packages. The result from the analysis of interviews with 25 consultants and experts in the ERP field recommends 14 customization strategies of an ERP package in the four areas of a firm: management, technology, organization, and environment. The analysis of the feedback from the consultants and experts generates the ranking of the 14 customization strategies.