In this special issue of Historical Social Research, indicators are considered epistemic devices that render the world governable by quantification. While endowed with an aura of objectivity, indicators are not neutral devices. Instead they transform the world they claim to describe. Against the backdrop of a global proliferation of indicators, we argue in favour of research that strategically focuses on the processes that lead to the institutionalisation and systematic use of key indicators in politics compared to cases in which these processes fail. This type of research strategy could enhance the accumulation of systematic knowledge as well as the relevance of social studies of quantification. Furthermore, we propose a heuristic for analysing how indicators are involved in shaping imaginations of the future following the three distinct dimensions of meaning (factual, social, temporal) as introduced by Luhmann. We also review diachronic and synchronic approaches to analysing the genesis and use of indicators in order to derive testable hypotheses about the gap between indicator design and policy use. Finally, we introduce the articles of this special issue.