In this paper, we explored how political knowledge related to generalised prejudice, defined as the common variance of three highly correlated specific prejudice concerning ethnicity, gender and sexual orientation. We aligned our hypotheses with the Cognitive Ability and Style to Evaluation (CASE) model, which postulates the mechanism underlying the relationship between individual-level cognitive variables and intergroup outcomes. As knowledge in its many forms correlates with and serves as a proxy of cognitive abilities, we hypothesised that political knowledge, when considered a precursor of prejudice, can be expected to act similarly to cognitive variables within the CASE model. We performed an empirical test of the hypothesised relationships on a nationally representative sample of Croatian students in their final year of secondary education (aged 17-19). As expected, there was a significant negative association between political knowledge and generalised prejudice, both direct and indirect via right-wing authoritarianism. Youth with higher political knowledge had significantly lower levels of generalised prejudice. In addition, while there were differences in the overall levels of political knowledge, right-wing authoritarianism and generalised prejudice between students attending different secondary education programmes, the pattern of relationships between these concepts was found to be stable across educational settings.