It has been a common assumption in sociology that the usefulness of knowledge on ‘the social’ is largely dependent on its ability to offer a truthful, complete and reliable account of social life. However, the efforts to produce instrumental social knowledge or to establish the ‘applied sociology’ have often been viewed as hindered by such difficulties as the overwhelming complexity of social phenomena and the alleged epistemological ‘deficiencies’ of the social sciences. This article starts by revisiting these arguments as underpinned by the representational understanding of knowledge as ‘the mirror of the world’, and then draws on social studies of science to articulate a different, pragmatic and translational understanding of knowledge as ‘a tool’. The two analytical views are then employed to account for the practical success of so-called user experience research – a relatively new and increasingly popular domain of the production of social knowledge to be used in the process of designing digital products like mobile apps and services. The article argues that the usefulness of knowledge generated in this field cannot be attributed to its epistemological superiority or theoretical edge, but rather to maximising the ability to engage, provoke understanding, foster collaboration and create action possibilities for the specific recipients of knowledge. These effects are achieved by simplifying the analytical framework and loosening methodological rigour, but also by offering innovative methods of articulation of research results and benefiting from the generative capabilities of knowledge. The article concludes by outlining the complex consequences of the translational and pragmatic approach to producing social knowledge.