Vincent Boucher, Yann Bramoullé, Habiba Djebbari, and Bernard Fortin, "Do Peers Affect Student Achievement? Evidence from Canada Using Group Size Variation," Journal of Applied Econometrics, Vol. 29, No. 1, 2014, pp. 91-109. The data used in this paper are the property of the Quebec Ministry of Education, Recreation and Sports (MERS; Canada), which does not permit us to share these data and requires that we destroy all data after August 2013. Permission to obtain these data from the MERS may be obtained after submission of a form to the Commission d'accès à l'information du Québec. The form is called the "Application for authorization to obtain nominative information for research, study or statistical purposes" and is available at http://www.cai.gouv.qc.ca/. The data are selected from the June 2005 Standardized Ministry Examinations (Épreuves Uniques du Ministère pour Juin 2005). We obtained from the MERS a sample from the population of all pupils registered in Secondary level 4 and Secondary level 5 in 75% of all schools that offered standardized examinations in the academic year 2004-2005. Please address any questions to: Bernard Fortin, Dept. of Economics, Université Laval, G1V 0A6, Quebec, Canada. bernard.fortin [AT] ecn.ulaval.ca