Accreditation is an essential component in the history of education in the United States and is a central catalyst for quality education, continuous improvement, and positive growth in student achievement. Although previous researchers identified teachers as an essential component in meeting accreditation outcomes, additional information was needed about teacher attitudes toward the accreditation process and professional development in relationship to actual accreditation outcomes. The purpose of this quantitative causal-comparative study was to investigate how teacher attitudes toward the school accreditation process and professional development, or an interaction between the two variables, effected their schools' accreditation outcome scores. Participants included 61 teachers from four schools accredited by AdvancED. Data was collected using the Questionnaire on the School Accreditation Process to determine teacher attitudes toward the accreditation process (positive or negative) and the Teachers' Attitudes about Professional Development instrument to determine teacher attitudes of professional development (positive or negative). The findings indicated that accreditation outcome scores were significantly higher in teachers with positive attitudes toward the accreditation process than teachers with negative attitudes toward the accreditation process. Recommendations for practice included: stakeholders continuing to provide resources for teachers to successfully implement accreditation processes; educational leaders identifying, implementing, and embracing accreditation processes that enable teachers to focus on continuous improvement and student achievement; and robust professional-development programs to help teachers be successful and grow as professionals. Recommendations for future research were also offered. [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.]