Advanced Placement for All (AP for All) is a high school reform movement designed to address systemic inequities in student access to advanced coursework. However, the evidence of the impact of the AP Program for traditionally underrepresented students is mixed. One way to view AP for All is as one of many examples of promising initiatives which, once scaled across innumerable schools, fail to meet expectations. This leads to predictable cycles of adoption that often end in abandonment. Improvement science seeks to break this condition by incorporating systematic improvement processes into promising reforms. This qualitative study applied improvement science to a single school's AP for All Program. Interviews with teachers and leaders were used to create a driver diagram to visualize the school's collective theory of improvement for their AP Program and answer the following questions: (1) What is the AP for All Program at the school that is the site of the study attempting to do? How do different stakeholders (teachers and school leaders) describe the theory of improvement of the school's AP for All model, and to what extent are they aligned or inconsistent? (2) How does the process of creating a theory of improvement model contribute to practitioner understanding of their AP for All Program? (3) For educational leaders, what is the value in using a driver diagram in practice to understand a program that is multiple years into implementation? The driver diagram revealed overall alignment between stakeholder groups of the AP for All Program goals as well as the primary and secondary drivers, which are the systems designed to meet the program goals. The diagram also called attention to drivers where teachers and leaders differed in their views. Engaging teachers and leaders in the driver diagram results yielded insights into how teachers and leaders viewed those differences and the ways in which they planned to use the knowledge from the study in their own practice. This study supported a school community with learning about their AP for All Program and contributed to the research on how elements of improvement science might deepen school implementation. [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.]