Enterprise Systems (ES) are often presented as a driver for business by providing business process integration and utilisation of technology in organising. However, the majority of the ES research is centred on the implementation phase and pre-implementation and post-implementation phases remain largely ignored. Another gap in the existing literature is that it usually ignores the implementation context in theorising. This study focuses on the procurement process of a public service organisation and analyses three instances of ES procurement in the case organisation. The data collection and analysis are conducted using the theoretical lens of socio-technical systems (STS) theory. It notes that while the work-system level and organisation-system level factors play some role in the ES procurement, macrosocial level factors (institutional context and the ES market) play a more important role in the public service context. It also notes the demonstrative nature of certain elements of the ES procurement process in public service organisations. In this way, this study brings out the complexity of ES procurement in public service organisations that result from the interplay of factors operating at work-system, organisational, and macro levels.