Staff at the ICILS international study center (ISC), in close collaboration with staff in the participating countries’ ICILS national centers, developed an international English version of the ICILS assessment and questionnaires. Countries subsequently translated and adapted these materials to their languages of instruction. Throughout this process, the overarching aim was to create high-quality instruments that were internationally comparable yet also appropriate to each country’s national context and education system. The detailed guidelines on translation and adaptation provided to all participating countries are described in the ICILS 2013 Survey Operations Procedures, Unit 3 (ICILS International Study Center, 2012).