Enterprise Resource Planning (ERP) systems are widely implemented in companies’ operation management and there are already a number of commercial-off-the-shelf (COTS) ERP products on the market. However, companies often have difficulty in identifying the requirements for selecting an ERP system, and also in specifying their objectives in an ERP implementation project. Despite the available information on ERP implementations, companies need a how-to method to support them in gathering and analyzing their ERP requirements. This qualitative empirical research deals with the development of a Customer-Centered ERP Implementation (C-CEI) method for the analysis of ERP system requirements. The development is conducted using an action research approach. The C-CEI method utilizes the principles and process of User-Centered Design (UCD) that aims at involving end users in the early stages of the product development. The results of this research are divided into four parts: (1) the C-CEI method itself, (2) the lessons learned from four companies that participated in the development of the C-CEI method, (3) content analysis of C-CEI documents produced in the companies, and (4) interviews of the companies’ personnel who had participated in the development of the C-CEI method. This research guides practitioners in how the ERP implementation can be approached employing a pre-defined method, and how the shared understanding of the ERP project objectives and activities are achieved within the organization. For academics, this study directs the research interest towards developing scientifically-based ERP implementation methodologies to complement those currently provided by ERP vendors and consultants