Enterprise Resource Planning (ERP) packages have been widely adopted and it is becoming clear that this is driven by multiple rationales that may be simultaneously at odds and complimentary. In this paper, we aim to develop a greater understanding of these rationales by taking ERP packages to be innovations and analysing their adoption with reference to the theory of diffusion of innovations. In particular, we consider the attributes of ERP packages that may affect their adoption such as relative advantage, compatibility, complexiblity, trialability and observability. We argue that users’ perceptions of these attributes are not always accurate and these ’misconceptions’ can further explain reasons for ERP adoption or rejection. Although our analysis aims to provide rich insights into the adoption of ERP packages, the results of the study are arguably of further interest to the more general study of packaged software and the more established literature on custom development.