This chapter examines the contribution of International Association for the Evaluation of Educational Achievement (IEA) studies—particularly the International Civic and Citizenship Education Study (ICCS)—to the development of democratic learning environments. It also highlights how ICCS has deepened knowledge and understanding of the importance of fostering such environments for students’ civic learning and engagement. The opening section introduces the main aims and characteristics of ICCS. Subsequent sections draw on data from the student, school, and teacher questionnaires to illustrate how ICCS informs the creation of democratic learning environments. Key areas addressed include openness of classroom climate, student participation in classroom activities, diversity-related activities, teaching and learning strategies, civic-related practices in the local community, and collaboration between schools and the local community. This chapter also provides practical suggestions for teachers on how to address these topics with their students, both at the classroom and whole-school levels. Finally, the chapter highlights how the development of democratic learning environments is linked to students’ civic knowledge and their engagement in democratic life.