In this chapter we present the factors for the success of ERP implementation projects. In the first section, we present the outcome of three surveys on the process and success factors for ERP projects. The first survey was undertaken in 2003 in Germany, the second in 2004 in the United States, and the third in 2006 in Turkey. The results are discussed in light of Hofstede's model of cultural factors. In the second section we evaluate common ERP lifecycle models. In spite of the great variety of potential advantages, it is also necessary to illuminate the real effects of standard ERP software in practice. Recent studies have revealed that 81% of German companies interviewed using SAP do not fully exploit the software's ability to optimize business processes, though 61% stated that SAP offers very good process optimization opportunities (Ploenzke, 2000). Therefore we evaluated popular lifecycle models with respect to their suitability to implement standard software in a process-driven way (Kuehl & Knoell, 2002). In the third section we present a semi-process-oriented approach lifecycle model for the implementation and release changeover of ERP systems. This lifecycle model was developed from the authors' experience in practice, and its practical relevance was evaluated in real-world projects. This approach is also assessed in light of the criteria presented in the second section.