This paper argues that ERP systems take the part of an organization’s administrative paradox. An administrative paradox is two sides of the same coin when coordinating organizations – the concurrent striving for flexibility and stability. The analysis of the ERP system is based on an interpretative and qualitative case study of an engineering firm. The theoretical lens used in this paper is structuration theory. One important point in this paper is that information systems can be viewed as a means to formalise coordination from an interpersonal level to a systemic one. This can, for instance, be realised through demands of input, process, and results of actions. In this way information systems can make a contribution to organizing ideals such as reliability and the achievement of sensible outcomes. On the other hand (as part of the administrative paradox) the use of information systems can institutionalize operating procedures and certain patterns of communication and coordination, restrain reorganizing activities and changes in control- and power structures. The information system’s constitutive role (consisting of a set of rules and resources, facilitating and constraining, coordinating, human action) is definitely an important issue when implementing, using, and improving ERP systems in organizations.