The purpose of this quantitative study is to analyze data around school culture and climate during the authorization process of the International Baccalaureate Diploma Programme. Data collected was analyzed to test the hypothesis that the authorization process serves as a "weeding out" of students by causing a significant difference to the culture and climate of the school. The study also tested the hypothesis that the school leader has an influence on the culture and climate of the school during this process. With this being the first study of its kind focusing on the differences in culture and climate of a high school during the authorization process of the diploma programme, results were unexpected, but provide profound suggestions for effectively leading this process. [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.]