A quasi-experimental research study is reported in this paper. Its aim was to evaluate the effects of different types of pedagogy on the cultivation of students' critical thinking dispositions. One hundred and forty Secondary 4 students (i.e. tenth-grade students at 15–17 years of age) from two Hong Kong schools joined a teaching intervention in which they learnt strategies of argumentation through an established critical thinking framework (i.e. Kuhn's model The Skills of Argument, Cambridge: Cambridge University Press, 1991]). Analysis revealed collaborative group work to exert positive impacts on students' development of critical thinking when used in conjunction with explicit instruction in reasoning and evidence-based justifications during the intervention. The research results also showed the students who received teacher guidance to have engaged more interactively in joint learning tasks, thereby illustrating the important role of the teacher in facilitating group discussions. [Copyright of Thinking Skills and Creativity is the property of Pergamon Press.]