International teachers and schools are a tremendous part of globalization, creating opportunities for cross-cultural exchange and understanding, innovative educational practices, and technological advancements. These schools offer educators from various countries the chance to share their expertise and collaborate on developing and improving the quality of education across internationally based schools. This case study dissertation explores how international school teachers adapt through a four-phase onboarding program to enhance teacher retention. Utilizing the theories of organizational socialization and social exchange, this study investigates whether onboarding and support systems help teachers feel fully integrated and supported in their work and personal lives as they adjust to a new geographical location and context. The data gathered through this case study confirms what previous studies have found throughout the last decade: that onboarding can significantly impact and influence teachers' retention and adjustment to a new country. This study focused on the first three onboarding phases: pre-onboarding, orientation, and training. This case study contributes to the international teaching field by highlighting the importance of these programs. It underscores the need for schools to invest in robust onboarding programs to promote long-term success and satisfaction. By providing these insights, this case study aims to encourage school leaders and human resource departments to focus on implementing a robust onboarding program. [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.]