Purpose: The purpose of this study was to determine the extent to which California public high school principals perceive the WASC Self-Study Process as a valuable tool for bringing about school improvement. The study specifically examines the principals' perceptions of five components within the Self-Study Process: (1) The creation of the Self-Study Document; (2) The development of ESLRs; (3) The implementation of ESLRs; (4) The development of the Action Plan; (5) The implementation of the Action Plan. The study also examined the differences in perceptions of principals based on the accreditation term their school was awarded and their school's API scores. The relationship between the accreditation term awarded and API scores of the schools in the study was also examined. Methodology: Multiple quantitative methods were selected for this study utilizing three research methodologies: descriptive, ex post facto, and correlational research. A total of 216 public high school principals, who went through the WASC Self-Study Process in the 2005/2006 school year were surveyed as the sample for this study. Findings: Examination of the descriptive data in this study indicates an overall positive perception that the WASC Self-Study Process brings about school improvement. The development and integration of ESLRs was perceived as less beneficial than the development and implementation of the Action Plan. Differences in perceptions based on accreditation term and API scores varied, however fewer differences were indicated in regard to ESLRs than the Action Plan. A relationship between accreditation term and API scores was identified in the study. Conclusions: Schools must approach the WASC Self-Study Process as a valuable tool for school improvement and not an exercise in achieving an accreditation term. Although each component of the Self-Study Process has a distinct value in itself, the Action Plan is considered to have the most impact in bringing about school improvement. Recommendations: Further research into this area is advised including replications of this study with a sample of principals from other accreditation years and other types of schools. A replication of this study with an extension to include the perceptions of teachers, students, parents, and other stakeholders is also advised. [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.]