The IEA International Computer and Information Literacy Study (ICILS) investigates the capacities of young people to use information and communications technology (ICT) productively for a range of different purposes, in ways that go beyond a basic use of ICT. ICILS 2023 includes authentic computer? Based assessments that are administered to students in their eighth year of schooling. These generate data reflecting two dimensions of ICT? Related capacities: computer and information literacy (CIL); and computational thinking (CT). This chapter describes the place of ICILS as part of the history of IEA studies, the relationship between ICT and educational processes, as well as factors related to the pedagogical use of ICT, since the late? 1980s. The relevance of ICILS to supranational policy development and monitoring (such as by the United Nations and the European Commission) monitoring of digital skills) is discussed, as are national policy and program initiatives in CIL and CT education in ICILS countries. The chapter further includes a summary recent research publications using ICILS data. The chapter concludes with summary information describing the ICILS study design, including the study research questions, new areas of focus in the study and the target population definitions and sampling procedures.