This article identifies the actors and dynamics involved in the process of ‘indicatorization’ in the aid effectiveness regime, from the initial decision to use indicators to the impact the indicators’ monitoring produces. It contributes to the existing and growing literature on indicators, and gives a specific example of the use of indicators in global governance. Because of its iterative perspective, the aid effectiveness regime enables an analysis of the trial and error process in the making of indicators and of the interplay of different actors, mainly States and international organizations, over time. This case study shows how actors can ‘play’ with indicators that are supposed to define their actions, and ultimately the tension that might exist between the indicator’s logic (the uniformity of the numerical measurement) and the regime principles, based on the ownership paradigm.