Current developments in information systems (IS) evaluation emphasise stakeholder participation in order to ensure adequate and beneficial IS investments. It is now common to consider evaluation as a subjective process of interpretation(s), in which people’s appreciations are taken into account to guide evaluations. However, the context of power relations in which evaluation takes place, as well as their ethical implications, has not been given full attention. In this article, ideas of critical systems thinking and Michel Foucault’s work on power and ethics are used to define a critical systems view of power to support IS evaluation. The article proposes a system of inquiry into power with two main areas: 1) Deployment of evaluation via power relations and 2) Dealing with ethics. The first element addresses how evaluation becomes possible. The second one goes in-depth into how evaluation can proceed as being informed by ethical reflection. The article suggests that inquiry into these relationships should contribute to extend current views on power in IS evaluation practice, and to reflect on the ethics of those involved in the process