The adoption of inter-organisational systems (IOS) has been reported to be slow in the industry. The slow diffusion of IOS has attracted considerable research attention. However, little has been done to address why organisations adopt these systems. We argue that IOS adoption is contingent upon how the motivations for adoption arise in organisations. We also suggest that the activities initiated by organisations to introduce IOS successfully are related to the organisation’s motivations for IOS adoption. To this end, a model of motivations for IOS adoption is proposed and some empirical evidence drawn from four case studies is presented. The findings indicate that the logical deductions drawn from the model in broad terms are consistent with the actual IOS adoption experiences of the case organisations.