In recent years, a large amount of Chinese international students, from middle or upper-middle class families, began their international education in Canadian secondary schools, where critical thinking is the main educational goal and often determines students' achievements. Guided by reflexivity in multilingual and intercultural education, this ethnographic study explores potential ways to foster Chinese international secondary school students' critical thinking in a second language, and the host country's socio-cultural contexts. Following 11 students' academic learning experiences in two English language and literacy courses in a Canadian international secondary school, this paper examines how language, social, and cultural factors affect learning and thinking processes. The findings challenged the stereotypical view that Chinese international students lack critical thinking skills. Insufficient English language competence and a lack of Western socio-cultural knowledge determined students' responses to learning content, the challenges they met in engaging with learning materials, and their critical and reflective judgements. This study underscores educators' and Chinese international students' reflexivity in their linguistic repertoires, and the socio-cultural effects on multilingual and intercultural education. Based on these results, teachers and students should employ a dialogic pedagogy to constructively negotiate learning and thinking.