This chapter discusses the importance of teacher knowledge, beliefs and attitudes in inclusive foreign language education. It outlines the pedagogical principles of an award-winning teacher training course, the Dyslexia for Teachers of English as a Foreign Language (DysTEFL) course that assists language teachers to apply inclusive teaching practices for dyslexic language learners. Teacher training schemes and teacher training materials, among other factors, directly impact the foreign language education ecosystem, and shape the way both teachers and their learners function in it. Teacher-knowledge studies highlight the potential of professional training in increasing and strengthening teacher knowledge, which in turn leads to facilitating student achievement via the use of effective instructional and classroom management practices. The DysTEFL course was designed so that it offers a broad array of expected learning outcomes in terms of knowledge, skills and social competence. The social interactions in the guided learning tasks help trainee teachers to co-construct knowledge and contribute to their development as teachers.