This study examines the general question of how classroom characteristics are linked with differences among students in civic competence, which is seen to be an important basis for political inequality. A resource-mobilisation account of youth civic competence is presented, and this is tested using hierarchical linear modelling and International Civic and Citizenship Study 2009 data. The determinants of youth civic competence are explored at the individual, family, and classroom levels, where resource and mobilisation factors at each level are examined. Evidence for classroom effects are tested using Campbell's compensation hypothesis and insights derived from Marsh's big-fish-little-pond effect (BFLPE). This case study of the Czech Republic shows limited evidence for an open classroom climate reducing civic competence differences between low- and high-SES students, and no evidence of BFLPE increasing such differences among youths.