Cheti Nicoletti and Birgitta Rabe, "Sibling Spillover Effects in School Achievement", Journal of Applied Econometrics, Vol. 34, No. 4, 2019, pp. 482-501. The data used in this paper are the property of the English Department for Education. Data access is through Office for National Statistics (ONS) remote access. For more details contact research.support@ons.gov.uk. For details of the application procedure see https://www.gov.uk/guidance/how-to-access-department-for-education-dfe-data-extracts We use Key Stage 4 data linked to the Spring Pupil Census data for academic years 2006/07-2009/10. We also use 2006/07 Pupil Census data including address data to generate sibling identifiers. Moreover, we merge to each student the code of their primary school attended from Key Stage 2 pupil data. Most of the variables used are directly taken from these data sets, in particular: GCSEs (Key Stage 4) in English and Mathematics, Key Stage 2 National Curriculum tests in English and mathematics, year of birth and gender of the student, ethnicity, whether or not the first language spoken at home is English, any special educational needs identi fied by the school for the child, eligibility for free school meals, area of residence and identifiers for schools and cohort. Further variables were derived as follows: Sibling identifier: We derive the sibling identifier from the 2006/07 Pupil Census data by considering all pupils in state schools aged 4-16 and living together at the same address in January 2007 (see Nicoletti and Rabe 2013 for details). Secondary school new mates: We use each older sibling's primary and secondary school code to identify the secondary school peers that are new to her. Average subject-specific ability in primary school is defined across all new peers, excluding the older sibling him/herself. Sample restrictions are described in the Data section of the paper. Our estimation sample contains two observations per student, one for English and one for Math. All variables (standardised Key Stage 4 test scores of the older and the younger sibling, standardised Key Stage 2 test scores, mean of the older sibling's new peers' Key Stage 2 percentile) apart from gender-by-subject interactions are expressed in deviations from the mean across subjects. Birgitta Rabe brabe [AT] essex.ac.uk