This article is an introduction to a European Educational Research Journal special issue on accountability policies and instruments in Europe. Two hypotheses grounded in the new institutionalist theory are presented to conceptualise and analyse the variety of national trajectories and forms of accountability in four European education systems (French-speaking Belgium, France, Spain and Portugal). The first hypothesis is that of path dependence, which privileges the prevalence of national histories despite the diffusion of global instruments. Strong resemblances between the countries, meanwhile, would favour the second hypothesis of a globalised field in which education systems are exposed to similar policy schemes.