In the Iranian education context where the concept of Sustainability Education is to a certain extent novel and fresh, one must first determine the state of Sustainability Education in education systems and specifically TEFL departments to discover EFL instructors' needs. This way, EFL instructors can be equipped with Sustainability Education competencies needed for transforming EFL education systems. Sustainability Education can be best implemented through language learning and specifically English learning compared with other subjects because language classes are the best sights for discussing sustainability issues. Additionally, the actualization of Sustainability Education in language classes can facilitate CLT and global citizenship operationalization. Having these in mind, the present study attempts to depict a clear picture of Sustainability Education among EFL instructors and provide education systems and policymakers with the necessary Sustainability Education competencies to equip teachers and help learners to feel and identify the relationship among sustainability issues such as culture, ecology, economy, power structures, and even their own families. The study was conducted using a Sustainability Education questionnaire developed by the researchers. The questionnaire was distributed among 150 EFL instructors. The findings of the study reveal that EFL instructors experience an apparent lack of sustainability literacy. On the other hand, their level of implementation is better than literacy but still not much satisfactory. The important findings can bring about the transformation and modification of EFL teacher education and curriculum and will be highly advantageous regarding professional and ethical dimensions of education system.