Test-based accountability or ‘TBA,’ as a core element of the pervasive Global Education Reform Movement (GERM), has become a central characteristic of education systems around the world. TBA often comes in conjunction with greater school autonomy, enabling governments to assess ‘school quality’ (i.e. test results) from a distance. Often, quality improvement is further encouraged through the publication of these results. Research has investigated this phenomenon and its effects, much of it focusing on Anglo-Saxon cases. This paper, drawing on expert interviews and key policy documents, couples a policy borrowing with a policy instruments approach to critically examine how and why TBA has developed in the highly autonomous Dutch system. It finds that TBA evolved incrementally, advancing towards higher stakes for schools and boards. Further, it argues that school autonomy has been central to the development of TBA in two ways. Firstly, following a period of decentralisation that increased school(board) autonomy, the Dutch government saw a need to strengthen accountability to ensure education quality. This was influenced by international discourse and accelerated by a (politically exploited) national ‘quality crisis’ in education. Secondly, the traditionally autonomous Dutch system, shaped by ‘Freedom of Education’, has at times conflicted with TBA, and has played a significant role in (re)shaping global policy and in mitigating the GERM.