The purposes of our study were to develop and validate a test for measuring Korean elementary and middle school students' information and communications technology (ICT) literacy and to make suggestions for improving ICT literacy across Republic of Korea. To those ends, we conducted a literature review, consulted expert opinions, administered a pilot test to 1086 students, and ultimately developed and validated an ICT literacy test by measuring and analyzing the ICT literacy of approximately 15,000 students in Korea. Results indicated that the ICT literacy of elementary school students was low (i.e., an average of 19 out of 35 possible points) and that students in lower grades had lower average scores. Regarding abilities within ICT literacy, problem-solving and information analysis and evaluation were relatively high among elementary school students, whereas information organization and creation, computational thinking, information searches, and information communication were relatively low. Among middle school students, ICT literacy was also low (i.e., an average of 18 out of 35 possible points), and eighth-grade students demonstrated lower literacy than seventh- and ninth-grade students. Although the difference among those grades was minor, the gap in ICT literacy did become greater as students get older. Regarding abilities within ICT literacy, information utilization and management was high among middle school students, whereas all others were low, particularly computational thinking. Drawing from those findings, we recommend a few methods of improving the ICT literacy of elementary and middle school students in Korea.