This paper addresses the perception that school Principals have of the “soft” accountability tools that have recently been implemented in the educational system of the French-speaking Belgium, and further, how the Principals themselves promote the use of these tools in a context characterized by quasi-market regulation and decentralization. These tools are external tests and documents related to these tests that we call “reflexive instruments” because they are assumed to increase the teachers' reflection on their own practices (without penalty/reward). 29 semi-structured interviews with high school principals were conducted. The analysis of the material shows that the tests perturb the schools more than the reflexive instruments do. This is because the tests promote identical standards and methods in schools, which sometimes differ significantly from those applied by the organizations. When tests are mandatory and have an impact on a student passing the class or not, schools that are removed from this standard fear for their position/identity in the quasi-market and protect themselves from potential effects of standardization. Thus we hypothesize that pressure to harmonize the schools operationalization (through testing) is in conflict with their need to profile themselves in the quasi-market.