The purpose of this study was to measure the impact of a year-long professional development plan designed to support K-3 teachers in two elementary schools in making shifts to align instructional practices with the science of reading. This mixed methods approach incorporated an action research design to answer the following research questions: "What was the relationship between teachers' understanding of the foundational skills of reading and teachers' confidence in teaching the foundational skills of reading?" "What impact does strategic and ongoing PD in the science of reading have on teachers' practice?" "What are teachers' perceptions of year-long professional development in the science of reading?" A synthesis of research on professional development and pre-survey data were used to inform the development of the plan and post-survey data were used to measure its impact on teachers. Findings revealed in focus group data substantiated the positive results obtained through the surveys. Findings also suggest that designing professional development based on research, combined with district and teacher needs can have powerful results and enact change. Recommendations for other districts interested in implementing ongoing professional development to impact instructional changes include designing a logical, focused delivery of content responsive to teacher's needs, using curricular materials during training, and providing coaching support. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]