Addressing the needs of students with dyslexia requires an in-depth knowledge of various components of a multi-dimensional approach to reading intervention, which is supported by an understanding of the structure of the language being taught. The current study explored the association between teacher knowledge of the English language and different stages of training provided through 2-year courses that meet the objectives of the International Dyslexia Association (IDA) standards of teacher knowledge and practice. It included 347 K-12 licensed teachers who were at various stages of training when they completed a test of knowledge in the areas of Phonological Sensitivity, Phonemic Awareness, Decoding, Spelling, and Morphology. The level of terminal degree (i.e., BA or MA) held by participating teachers and their amount of teaching experience did not predict performance on the test. In contrast, participating teachers differed in their level of knowledge as a function of how much training they had received as part of a 2-year course. Increased training was associated with elevated levels of knowledge. Moreover, teachers who completed the 2-year training program and went on to obtain certification through a national certifying organization had reliably greater knowledge than those who had not. Additionally, the weakest domains of knowledge across all teachers were in spelling and morphology, suggesting a need for improved training in these domains, given that they are identified deficiencies for persistently poor responders to reading intervention and in children presenting with late emerging forms of reading disability.