The discourse of quality has permeated everyday discussions about education, yet the concept as such remains complex. Moreover, during the constant struggle to improve educational quality, governments have increasingly devoted attention to the results of international large-scale assessments. As those results are used to inform policy decisions to improve countries' educational quality, it is important to understand how this concept of quality is appropriated. As a synthesis of how quality is conceptualised and operationalised in this body of research is lacking, the current paper seeks to fill that gap by presenting a systematic review. Our analysis identified definitional patterns and explored the corresponding methods for measuring quality. Based on this analysis of the reviewed studies, a framework of four approaches towards quality emerged to render the concept more accessible. In light of these results, benefits and limitations of the concept's complexity are discussed, and implications for research are forwarded.