The main objective of this project deliverable is the preparation of data harmonisation guidelines for education research. The document is divided into two sections, the first section overviews the national and international data available in each partner country (Finland, Germany, Hungary, Ireland, Lithuania, Luxembourg, Norway, Spain and Switzerland). The goal being to provide an as comprehensive as possible list of the data sources that address education-related themes throughout the life course and provide relevant information concerning the focus of each study, it’s accessibility and it’s main target group(-s). The second section provides proposed harmonisations for the key variables across the surveys retained for empirical analysis (PIRLS, TIMSS, PISA, EUROSTUDENT VII, PIAAC, LIS, Growing up in Ireland, NEPS SC4, and TREE2). The variables include those pertinent to the main axes of educational inequalities (such as gender, socio-economic status, migration background) and variables that measure either directly or indirectly educational outcomes. Each variable is harmonised by conceptual content (based on the variable definitions that are as similar as possible) and by coding structure (using the same units of measurement and coding values).