This article reviews the literature and presents data from a study that examined the effects of professional development in scientifically based reading instruction on teacher knowledge and student reading outcomes. The experimental group consisted of four first- and second-grade teachers and their students (n = 33). Three control teachers and their students (n = 14), from a community of significantly higher socioeconomic demographics, were also followed. Experimental teachers participated in a 35-hour course on instruction of phonemic awareness, phonics, and fluency and were coached by professional mentors for a year. Although teacher knowledge in the experimental group was initially lower than that of the controls, their scores surpassed the controls on the posttest. First-grade experimental students' growth exceeded the controls in letter name fluency, phonemic segmentation, nonsense word fluency, and oral reading. Second-grade experimental students exceeded controls in phonemic segmentation. Although the teacher sample was small, findings suggest that teachers can improve their knowledge concerning explicit reading instruction and that this new knowledge may contribute to student growth in reading. (Contains 7 figures and 1 table.)