In this chapter we look at the factors that influence the successful implementation of a global enterprise resource planning (ERP) system. We identify 12 issues that need to be considered when implementing such systems. Each one of these issues is expanded upon with relevant literature and examples. In this chapter we also look at factors that lead to the development of information systems by employees in addition to or outside the implemented ERP. We introduce the concept of feral systems to explain this phenomenon. Other factors such as employee mistrust of the system are also discussed. Finally we look at future directions with respect to ERP implementations.