In 2013, a school district located in the northeastern region of the US implemented the Reading Street Common Core Program (RS), a highly structured and scripted reading program. The problem was that the program had an uneven effect on elementary level student reading achievement at Title 1 schools in the district. This qualitative case study explored how teachers, professional development lead teachers (PDLTs), and principals at four high performing schools (HPS) and four low performing schools (LPS) experienced implementation of the RS, and how their experiences explained the uneven effect on student reading achievement. The conceptual framework that grounded the study was the action theory of educational change developed by Fullan. Interviews were conducted with a sample of 10 teachers, two principals, and two PDLTs from eight schools. Data were analyzed using provisional codes, pattern codes, and thematic analysis. Study results did not explain uneven results of RS implementation. However, analysis indicated that both the HPS and LPS participants experienced similar challenges: inadequate time for teacher collaboration, lack of alignment between the district Curriculum Instructional Map (CIM), district writing curriculum, and RS, and inadequate support from school and district leadership. Findings informed a policy paper that provides recommendations for the district to implement. The study may contribute to positive social change by increasing district leadership awareness of how to improve the implementation of RS leading to improved student reading achievement. [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.]