In this chapter we report on students’ civic knowledge achievement in the International Civic and Citizenship Education Study (ICCS). The chapter begins with a description of the test instrument used to assess civic knowledge. This is followed by an explanation of the development and content of the ICCS civic knowledge proficiency scale used to measure and describe students’ civic knowledge achievement. The student test and civic knowledge scale are illustrated using example items from each level. We then describe students’ civic knowledge achievement within and across ICCS participants. We first report on students’ civic knowledge in ICCS 2022 and trends in achievement across cycles. While civic knowledge varied across countries, a consistent finding reported across all first three cycles of ICCS was that the variation of civic knowledge within countries exceeded the variation across countries. Furthermore, we observed a pattern of increases in student civic knowledge between 2009 and 2016 followed by decreases between 2016 and 2022. We then report on the associations between aspects of students’ background and their civic knowledge achievement. Consistent with findings from pervious ICCS cycles, female students demonstrated higher civic knowledge than male students, and student socioeconomic status, reported across a range of measures, was positively associated with student civic knowledge.