It has been over a decade since the Ministry of Education and Culture in Indonesia mandated teachers to foster critical thinking; however, studies document that in Indonesia, students’ critical thinking still lags behind other countries. This condition led us to investigate teachers’ understanding of critical thinking as they hold the central role in promoting it. This qualitative research survey involved 64 English language teachers who had signed up for a webinar about critical thinking. The respondents varied in terms of gender, educational background, and teaching experience. The questionnaire was distributed online, and their participation in filling out the questionnaire was voluntary. Questions were divided into two categories: the respondents’ demographic data, including gender, educational background, and teaching context. The second category focused on teachers’ understanding of critical thinking and its implementation in the classroom context. The study found that teachers do not yet have comprehensive knowledge about critical thinking, and this is reflected in their teaching practice and assessment of students’ critical thinking. Interestingly, the study revealed that only a few teachers realized that their difficulties in promoting critical thinking might derive from their limited understanding about the notion.