School systems are called not only to instruct and socialize students but also to differentiate among them. Although much research has investigated inequalities in educational outcomes associated with students’ family background and other ascriptive traits, little research has examined cross-national differences in the total amount of differentiation that school systems produce, the total achievement inequality. This article evaluates whether two dimensions of educational systems—variations in opportunities to learn and intensity of schooling—are associated with achievement inequality independent of family background. It draws data from the Programme for International Student Assessment for more than 50 school systems and models the variance in achievement. Findings suggest that decreasing the variability in opportunities to learn—in the form of greater homogeneity in teacher quality and the absence of tracking—within the school system might reduce achievement inequality. More intense schooling is also related to lower achievement inequality to the extent that this intensity is homogeneously distributed within the school system, particularly in the form of a more highly qualified teacher workforce.

In a resource-constrained world of an estimated 10 billion people in 2050 with the same material aspirations of today's high-income nations there is no question: The future economy will need to

Field-of-study mismatch occurs when a worker, trained in a particular field, works in another field. This study draws on the Survey of Adult Skills (PIAAC) to explore how skill supply and labour market demand dynamics influence mismatch. It updates cross-national estimates on mismatch and estimates the mismatch wage penalty. Findings suggest that around 40% of workers are mismatched by field at their qualification level, 11% overqualified in their field and 13% overqualified and working outside their field. The saturation of the field in the labour market and the transferability of the fields' skills predict the incidence of field-of-study mismatch and overqualification. Workers who are mismatched by field only suffer a wage penalty if they are overqualified.

OECD Working Papers should not be reported as representing the official views of the OECD or of its member countries. The opinions expressed and arguments employed are those of the author(s). Working Papers describe preliminary results or research in progress by the author(s) and are published to stimulate discussion on a broad range of issues on which the OECD works. Comments on Working Papers are welcomed, and may be sent to the Directorate for Employment, Labour and Social Affairs OECD,

This working paper was prepared by Francesca Borgonovi and Guillermo Montt of the OECD Secretariat. JT03321161 Complete document available on OLIS in its original format This document and any map included herein are without prejudice to the status of or sovereignty over any territory, to the delimitation of international frontiers and boundaries and to the name of any territory, city or area.EDU/WKP(2012)10 Unclassified English -Or. English EDU/WKP(2012)10 2 OECD EDUCATION WORKING PAPERS SERIESThis series is designed to make available to a wider readership selected studies drawing on the work of the OECD Directorate for Education. Authorship is usually collective, but principal writers are named. The papers are generally available only in their original language (English or French) with a short summary available in the other. This document and any map included herein are without prejudice to the status of or sovereignty over any territory, to the delimitation of international frontiers and boundaries and to the name of any territory, city or area.The opinions expressed in these papers are the sole responsibility of the author(s) and do not necessarily reflect those of the OECD or of the governments of its member countries.