School reformers are often searching for a program that will have a positive and far-reaching effect on a school campus. Researchers and writers have described the International Baccalaureate Diploma Program (IB DP) as a largely positive influence on a school campus, providing a rigorous and standards-based curriculum to IB DP students. However, there has been little written on whether or not the IB DP has an impact on a school culture and climate beyond the impact on the IB DP students. This qualitative study described the impact of the International Baccalaureate Diploma Program on the culture and climate of two high schools where the program was implemented. As there was a paucity of research that specifically addressed the impact of the IB DP on school culture and climate, some of the literature in this study focused on the history and background of the IB program, research that specifically described the IB DP, research on school culture and school climate, and literature that described systems thinking. The two schools were both located in Orange County, California. They were assigned pseudonyms, Washington High School (WHS) and Lincoln High School (LHS). Each of the school sites was examined and meaningful artifacts were collected. At each site, the researcher conducted three interviews and one focus group. After completing the interviews and focus groups and compiling field notes from the site and artifacts, the researcher reduced the data into codes and subsequently themes that were related to school culture and climate. Some of the codes had been decided upon a priori, but the themes were not established until after all the data had been collected and analyzed. With the use of narrative, the researcher described the impact of school culture and climate, as described by participants, within the six identified themes of school pride, IB diploma requirements, instructional techniques, school within a school, earned and entitled IB student privileges, and school mission and IB mission. In several of the aforementioned six themes, there was a mixed impact of implementing an IB DP on school culture and climate. Some of the evidence indicated that there was a marginal or slightly negative impact on school culture and climate. However, in examining all of the themes, the research suggests that schools that implement an IB DP experience a positive impact on school culture and climate. [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.]