ERP implementation is an expensive and extensive undertaking involving all activities related to planning, justification, installation, and commissioning of the installed system. An ERP system extends across the entire organization and beyond to cover integral partners in the supply chain. Furthermore, ERP projects can take two, three, or more years to fully implement . All of the above factors contribute to the complexity of ERP installations, and make snap-shot/cross-sectional approaches unsuitable for investigating the entire ERP implementation process. We adopt a case-study methodology to create propositions based on a longitudinal analysis of postimplementation factors that contribute to the successful installation and management of an ERP system. However, unlike the majority of studies in this area that focus on single case studies or survey information based on a specific ERP process or implementation plan, we develop propositions based on ERP implementations at eight diverse manufacturing facilities.