It is widely believed that critical thinking is vital for academic success or effectiveness and innovation in the workplace. However, there is insufficient knowledge about how language teachers conceptualise critical thinking and implement it in teaching. This is especially true in EFL contexts and at the secondary level. Against this background, this paper addresses the research gap to understand EFL teachers' conceptualisation and practice of critical thinking. This study adopts a funnelling approach. A broad overview of 182 EFL teachers' conception of critical thinking skills was investigated through a questionnaire, a smaller group of 12 teachers were interviewed in three focus groups to offer in-depth understanding, and three teachers were observed in teaching. The findings identify the key characteristics and elements of critical thinking from teachers' perspectives and shed light on how teachers use cultural and subject-specific genres to embody critical thinking in their conceptualisation. The findings suggest that teachers actively implement critical thinking in teaching. The classroom extracts reveal teachers' interactional strategies to enhance critical thinking. The findings have substantial implications for teacher learning.