This study examines conceptions of criticality and its instruction in the History learning environment in Sweden, Russia, and Australia as evidenced in one sample upper secondary class in each country. Transnational findings from an analysis of educational policy documents, teacher and student interview data, together with data from classrooms, reveal varied interpretations of the term criticality. While criticality is conceptualised as a generic skill of questioning at the overarching curriculum level, it is reconceptualised as a discipline-specific skill at the subject level. Discipline-specific conceptions include criticality as source criticism, as meaning making from historical evidence, as questioning historical narratives, and as educating for citizenship. The findings indicate that the visionary criticality objectives of the curricula might be more limited at the local policy level both as a result of interviewees' conceptions of criticality and classroom practicalities. This transnational study proposes some policy harmonisation measures towards equity of education with regard to criticality instruction for all upper secondary students, as required in the national curricula.