The KELS aims to collect information on students’ educational experiences and achievements and how the school environment influences development, ultimately to provide data for education policy. There are two cohorts in the KELS: the 2005 cohort and 2013 cohort, both recruited from schools across South Korea. The 2005 cohort includes almost 7,000 middle school students who completed baseline assessment in 2005 when they were in grade 7 and were followed every 1 to 2 years until 2020. The 2013 cohort includes over 7,300 elementary school students who completed baseline assessment in 2013 when they were in grade 5 and are being followed up every 1 to 2 years until 2030.