Students most at risk for reading-related disabilities frequently struggle with word recognition and oral language, including, in the earliest grades, specific skills related to phonological awareness and vocabulary. Classroom teachers' delivery of high-quality differentiated supplemental instruction may promote reading acquisition for these students. The current study examined whether the Targeted Reading Intervention, a webcam-coaching literacy professional development program for kindergarten and first grade classroom teachers, was more effective in producing reading gains for students who had the lowest scores on fall measures of phonological awareness and/or vocabulary as compared with students with higher scores. Findings revealed that students who participated in the Targeted Reading Intervention and who scored lowest on the fall vocabulary measure had the highest scores on spring decoding measures.