The IEA International Civic and Citizenship Education Study studied the ways in which young people in lower secondary schools are prepared to undertake their roles as citizens in a wide range of countries in Europe, Latin America, and the Asian-Pacific region. A central aspect of the study was the assessment of student knowledge about a wide range of civic and citizenship-related issues. This paper includes analyses that use a multi-level model to explain differences in civic knowledge on the basis of student characteristics, home background and school contexts. In addition, the analyses in this paper include a consideration of factors characterizing educational systems that may explain differences among countries as well as differences in within-country effects of student- or classroom-level variables. The analyses in this paper are based on data from approximately 140,000 students from 38 countries and comprise measures of student knowledge, attitudes, behaviors, and student background. Additional contextual data were collected using surveys of principals and teachers of the sampled schools and an online national contexts survey.