Considering the ongoing strive towards new, alternative indicators to measure our societal development pathways, and the fact that policy indicators remain largely enigmatic with regard to their patterns of embeddedness in institutional decision-making processes, it appears necessary to work towards reducing our lack of understanding of their interactions with policy-making. In the present paper, we focus on exploring the significance of composite indicators for policy making in the particular policy environment of the EU-institutions. Our research is underpinned by the conviction that such indicators are not systematically used directly, but have an indirect influence on policy making that needs to be better understood. Our analytical framework-in order to analyse the ways in which composite indicators enter policy processes is characterised by the distinction between the 'use' and the 'influence' of indicators on the one hand, and on the other hand between 3 types of factors: indicator factors, policy factors and user factors. Our empirical results show that while most of the academic attention and political debate around indicators has tended to focus on 'indicator factors', such quality attributes actually mattered relatively little in our setting as determinants of indicator influence. This rejects the idea that the robustness of evidence would lie exclusively in its technical quality and in the independence of its producer, and instead calls attention to the processes of evidence-construction. Simultaneously, 'user factors' (beliefs and representations of policy actors) and 'policy factors' (institutional context) were crucial as explanatory factors of the policy mechanics we identified.