As public school accountability for student achievement has continued to increase, prior to and as a result of the No Child Left Behind Act of 2001, schools have sought ways of bringing new instructional services to their students to raise their levels of achievement. Some Pennsylvania public high schools have attempted to improve student achievement by going through an accreditation process called the Middle States Association's (MSA) Accreditation for Growth (AFG) in addition to the mandatory strategic planning process. Controversy exists about the effectiveness of the process in improving student performance. Researchers have pointed to a significant overlap between the AFG process and the state mandated strategic planning process. The specific problem was that it had not been shown if the AFG process, in addition to the mandated strategic planning process, was effective in improving student achievement. Without this information, stakeholders such as high school principals and other administrators may not have had all the information they needed to make decisions regarding the AFG process, with the corresponding result that student achievement may suffer. This nonexperimental quantitative study collected student performance data to determine if there was a difference in student achievement between schools that had completed the AFG process and schools that had not among Pennsylvania's 745 public high schools. For the purposes of this study, the measures of student achievement were a school's average SAT score, graduation rate, and adequate yearly progress (AYP) in reading, writing, and math for the current year. The survey was responded to by 152 Pennsylvania public high school principals. This study showed MSA-AFG accredited schools had a statistically significantly larger average SAT score (p less than 0.001), a statistically significant higher graduation rate (p less than 0.001), and a statistically significant higher percentage of schools that met AYP in reading, writing, and math (p less than 0.001), compared to schools that were not MSA-AFG accredited. Therefore, the null hypotheses regarding the absence of a significant difference in student achievement were rejected. It is recommended that future research be conducted to include demographic information, school dynamics, and qualitative questions to increase understanding of this relationship. [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/en-US/products/dissertations/individuals.shtml.]