Canadian and Japanese secondary teachers' conceptions of critical thinking were compared and contrasted. Significant cross-cultural differences were found. While Canadian teachers tended to relate critical thinking to the cognitive domain, Japanese teachers emphasized the affective domain. The quantitative data, effectively reduced through factor analysis, showed a clear distinction and significant difference between Canadian and Japanese teachers on four of the five factors--Canadian teachers viewed critical thinking through "Cognitive Strategizing" and "Relevance", while Japanese teachers favoured "Conscientious Judgements" and "Intellectual Engagement". However, through further qualitative analysis, critical thinking was found to be a tacit and implicit teaching practice supported by most teachers surveyed, irrespective of gender, age, teaching experience, subject area and, most importantly, the cultures from which they came. (Contains 1 note and 4 tables.)