A policy for the external evaluation of schools has been developed over the last fifteen years in French-speaking Belgium. Our study analyses the reception of this policy by local actors (elementary school directors and teachers) and intermediaries (inspectors) and shows how the knowledge-based regulatory tools implemented by these actors affect the reception and legitimacy of the evaluation policy as a whole. Using the sociology of translation (Callon & Latour) and neo-institutionalist theory, we compare two methods for constructing and implementing this policy in two inspection zones. In the first, the apparatus relies essentially on bureaucracy, while in the second the policy is constructed via a network of local actors and intermediaries. We show that 1) the roles and strategies of the intermediate actors differ considerably. 2) The differences observed in the construction of the evaluation policy (the co-construction of tools by a network of intermediate actors on the one hand, and a hierarchical and bureaucratic implementation on the other) are linked to the various effects of the regulatory tools on teaching practices and that policy’s legitimacy.