Enterprise Resource Planning (ERP) systems have emerged and have matured to become the core of successful information management and the enterprise backbone of organizations for applications such as e-business, Supply Chain Management (SCM) and Customer Relation Management (CRM). This paper theorizes and generalizes the important steps and factors for ERP implementation success. First, the paper gives an introduction to ERP and the relationships between MRP, MPRII and ERP. The benefits and motivations of adoption of ERP systems are introduced. Steps for ERP system selection and implementation are presented. The paper proposes a qualitative analysis of the key factors that affect a successful ERP implementation.