In much of the enterprise systems (ES) literature shadow systems, although infrequently studied, are regarded as undesirable. They are believed to undermine ES implementation and as such should be eliminated. Using a theoretical framework that explains the motivation for the development of shadow systems within an ES context, this paper analyses a longitudinal case study of the eight-year rise and expected fall of a single shadow system. Results of the analysis indicate that shadow systems may be useful indicators of a range of problems with enterprise system implementation. It appears that close examination of shadow systems may help both practitioners and researchers improve enterprise system implementation and evolution.