This chapter explains the strength and weakness of the research and covers the main result that might shape the relationships between the evolution of enterprise resource planning (ERP) packages and information systems (ISs). It finds that links between ERP systems and ISs are triggered by certain variables or factors: economic crisis and competitiveness, total dependency on the ERP vendors, project management, interoperability and complexity of the ERP systems, evolution strategies of existing systems and of ERP vendors. Although the ERP system's implementation is logically a factor aiming to improve the IS integration, the negative values of the research factors could prevent this integration. These negative values, that are related to the ERP system's evolution, could also cause a kind of IS regression from a state of integration toward one of disintegration. The chapter summarizes the interactions between the research factors, the evolution of ERP systems and IS integration or disintegration.