The relationships among teachers' knowledge, use, and perceived effectiveness of inclusive instructional practices for students with emotional disturbance (ED) has implications for the provision of a free appropriate public education (FAPE). We unpacked these nuanced relationships through mediation analysis. Data for our study came from a broader survey investigation of inclusive instruction for students with ED in one of the northeastern states in the United States. The sample consisted of 176 teachers who were mostly female (85%) with an average of 12 years of teaching experiences. We found that (a) the relationship between teachers' reported knowledge and use of inclusive instructional practices was bidirectional, (b) special education teachers were far more likely to implement specialized instructional practices such as behavioural support and differentiation than general education teachers and (c) there were no reported differences in instructional practices (i.e. general practices) and classroom management between special education and general education teachers. Implications for pre-service teacher training, professional development and teacher support are discussed.