The main aim of this descriptive survey study was to explore Iranian EFL teachers’ knowledge, attitude, and practice of Critical Thinking (CT) skills. This study differs from previous studies in that the knowledge construct assessed was framed to find out if participants knew what the concept of core-skills of CT skills meant. Also, contrary to previous studies, the type(s) of CT skills (core and subskills) practiced within individual language skills training classes was studied in this study. To this effect, 276 male and female EFL teachers completed the Knowledge of CT skills, the California Critical Thinking Disposition Inventory and the Classroom Practice of CT skills pre-tested self-report questionnaires. Subsequent to running non-parametric one sample Wilcoxon Rank Order tests on the data collected, the most important finding in the present study was that the EFL teachers demonstrated poor overall knowledge of the concept of core CT skills though their attitude towards CT was significantly positive. The results also showed that overall, not much CT skills practice was implemented in language skill-based classes, especially in the listening classes where a significant number did not practice any of the CT sub-skills assessed. On the contrary, a significant number of teachers reported practicing almost all the CT sub-skills in their speaking classes. Thus, this study suggests that another important contributing factor of the lack of practice of CT skills in the EFL context to probably be teachers’ lack of understanding of the concept and skills related to the theory of CT. This is significant as it is believed that when teachers understand how theory informs practice, they usually come to be more open to the possibility that theory really matters in the context of education.