Reading scientists have reached consensus that learning to read requires mastering the foundational skills of phonemic awareness and phonics (Dehaene, 2009; Stanovich, 2000). However, scientifically-based reading research has not fully transformed instructional practice (Castles, Rastle, & Nation, 2018), thereby leaving a science-to-practice gap. This gap has proven challenging to close (Seidenberg, 2017). For example, foundational skills are taught in balanced literacy but are often not taught explicitly (Rayner et al., 2012; Seidenberg, 2017), nor to mastery (Moats, 2007). Additionally, identifying words using pictures and context cues before sounds/letters is used extensively in balanced literacy, despite no evidence to support this strategy for early readers (Kilpatrick, 2015). This qualitative study investigated two schools implementing scientifically-based reading instruction (SBRI) to determine what factors helped or hindered this transformational change. The research questions sought to determine what persuaded teachers to implement SBRI and what challenges either persisted or were overcome related to the knowledge, persuasion and implementation stages of Rogers' (2003) Innovation-Decision Process. Using case study methodology, data were collected via 36 interviews, document review, and observations of instruction and progress monitoring meetings. Inductive and deductive coding, using the Innovation-Decision Process were used for data analysis. Findings from this study indicated that teachers were persuaded to implement SBRI by its compatibility with the cultural norm of collaboration, compatibility with previous practices such as Readers Workshop, and by teachers' observations of improved reading achievement. Prior beliefs about reading instruction did not appear to persuade or dissuade implementation. Teachers were able to implement SBRI with adequate "how-to" knowledge but were limited by their lack of knowledge about the principles of the science of reading. Consultants with principles knowledge were able to guide the schools in implementing and improving their use of SBRI. Implications for practice were discussed related to how district instructional leaders might prepare for and successfully implement changing to SBRI. Implications for learning related to what district instructional leaders should know about SBRI so they can spot red flags in their district's reading curriculum. Implications for leadership related to how scientific reading leaders might help persuade district instructional leaders to embrace SBRI. [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://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]