The purpose of the current study is to investigate post-basic English teachers' knowledge, perceptions and practice of critical thinking skills and the challenges they face while teaching skills in EFL classrooms. Six research questions were investigated to achieve this purpose: 1. To what extent are EFL teachers knowledgeable about critical thinking skills? EFL teachers' knowledge about critical thinking skills vary according to gender? 3. To what extent do EFL teachers use classroom behaviors that nurture critical thinking at the post basic education schools? 4. Does EFL teachers' practice of classroom behaviors that nurture critical thinking skills vary according to gender? 5. What perceptions do EFL teachers show towards critical thinking instruction? 6. What challenges do EFL teachers face when incorporating critical thinking in their classrooms? Since the study focuses on teaching critical thinking skills in grade 11 and 12 classrooms, the sample that the researcher selected was mainly from all the schools that include both grades 11 and 12 students for the academic year 2014-2015. They are 12 schools: 3 female schools, 3 male schools and 6 mixed gender schools. The total number of grade 11 and 12 English teachers in these schools is thirty: 15 males and 15 females. To accomplish the objectives and fulfill the purpose of the study, the descriptive method was used to collect responses from the participants. The study employed a questionnaire and an observation form to help the researcher collect the data needed to answer the research questions. This study reveals that, based on teachers' self-reports of their knowledge of critical thinking skills, they have an average knowledge of critical thinking concepts and skills. In addition, the study reveals that there is a significant difference in teachers' knowledge of critical thinking concepts and knowledge in favor of female teachers. The study also reveals that post-basic English teachers rarely use the behaviors that murture critical thinking skills. On looking at the post-basic EFL teachers' use of behaviors nurturing critical thinking skills, the study reveals that there is no significant difference between males and females in the use of the behaviors that most nurture critical thinking skills, except for one type of behavior. Data shows a significant gender difference in the use of the behaviors inviting evaluation. This difference is in favor of females, indicating that female teachers use behaviors that invite evaluation more frequently than male teachers. The study also reports some challenges that EFL teachers face when teaching critical thinking; these are related to the course book, to extra curricular activities, to class size and to training.