One prominent finding from international large-scale assessments is that student achievement varies significantly across the world, leading to wonder why some educational systems perform better than others. This is, in fact, the main aim of educational effectiveness research (EER): identifying what works in education and why (Creemers & Kyriakides, 2008). EER results show that the influences on student achievement are multilevel, with factors operating at the student, classroom, school, and system levels (Kyriakides et al., 2017). Furthermore, EER studies have found that most of the variation in student achievement can be explained by the student and classroom levels, but the study of system-level effects is a fairly new research area (Scheerens, Luyten, van den Berg, & Glas, 2015). Therefore, the aim of this paper is to gather evidence regarding system characteristics that explain variation in different educational outcomes, both in the quality and in the equity dimensions of educational effectiveness. It is expected not only to identify what type of variables, both dependent and independent, have been studied in the literature but also to further develop the dynamic model of educational effectiveness (Creemers & Kyriakides, 2008), especially the wider educational environment aspect. For the selection of studies included in this systematic review, an electronic search based on the Scopus, Web of Science, ERIC and PsycNET databases was conducted. A study was included on our sample if it compared at least two educational systems and if it included system-level factors as explanatory variables of different educational outcomes. With the term ‘system’, we refer to studies comparing whole countries or districts and regions within a country. A total of 103 articles met the eligibility criteria and were included in this review. The studies come from several disciplines (i.e. educational science, economics, sociology, and psychology) and analyze a range of different factors (i.e., country income indicators, institutional features of educational systems, cultural values). Regarding response variables, the studies focus on student achievement in cognitive and affective outcomes of schooling, as well as on more general academic outcomes such as educational efficiency, school dropout, enrollment rates, and grade repetition.

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