Teachers' implementation of differentiated supplemental instruction is critical to help students with or at risk for reading-related disabilities acquire early reading and vocabulary skills. This study represents an initial investigation of whether classroom teachers' intervention fidelity (exposure, adherence, and quality) of targeted reading instruction (TRI, formerly called targeted reading intervention), a professional development program with embedded student intervention and weekly webcam literacy coaching support, was related to spring reading and oral vocabulary gains for students at risk for reading-related disabilities. The study also examined whether teachers' years of participation in TRI (1 year vs. 2 years) moderated associations between intervention fidelity and students' reading and oral vocabulary outcomes. Findings suggested that teachers' adherence to TRI strategies was directly associated with students' vocabulary gains as well as word reading skills for teachers in their second year of participation. Furthermore, when teachers provided students with more TRI exposure during their second year of participation, students made greater gains in word reading and reading comprehension.