In this paper we aim to situate social implications of information systems (IS) within a broader context of progressive rationalisation in modern organisations. More specifically, we examine what roles IS play in increasing rationalisation of organisational processes and what are the implications. Our objective in the paper is twofold: i) to propose a rationality framework that synthesises different approaches to reason and rationality, and ii) to demonstrate how it can be used as a conceptual model for critical analysis of social and organisational consequences of rationalisation in organisations enabled and supported by IS. By drawing on a field study in a retail company, we interpret three IS cases to demonstrate how the rationality framework helps explain different IS-organisation relationships in the light of increasing rationality that entails both substantial benefits and risks.