This quantitative study tests the relationship between ideological classroom composition and perceptions of open classroom climate. Using data from the 2016 International Education Association’s International Civic and Citizenship Study, the study uses latent class analysis and multilevel regression modelling across five countries. First, latent class analysis identified students as low or high socioeconomic status. To assess ideological polarization, the gap between support for gender equality and ethnic rights was calculated between groups. Finally, a multilevel regression model measured the relationship between ideological polarization and students’ perception of open classroom climate. Across three countries, results found negative associations between increased polarization and perception of an open classroom climate. Additional testing identified that polarization modified the relationship between student socioeconomic status and perceptions of open classroom climate in Croatia.