This mixed methods study sought to identify the incorporation of support for implementing evidence-based instructional practices within an MTSS framework among teachers and the impact on student growth outcomes in three K-2 schools. The study also determined teacher perceptions regarding how support in adult behavior change, which is the theoretical framework of the study, impacted a shift in their instructional practices utilizing a qualitative survey, one-on-one interviews, and two independent samples t tests. Participants in the study expressed that school climate, principal instructional leadership, purposeful PLCs, and their attitudes about new behaviors best supported them in adopting innovative instructional reading practices. Participants also expressed that students grew with the newly implemented practices; however, independent samples t-test data indicated no significant difference in student growth for teachers who perceived a high level of support with the instructional reading practices as compared to all other K-2 teachers. These findings suggest that adult change factors do support changes in teaching practices, but additional factors should be considered to see improvement in summative assessment data. [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.]