This qualitative case study explored the influence of self-reported intercultural competence (IC) on the teaching practices of adult English as a Foreign Language (EFL) teachers in culturally diverse online classrooms. The researcher examined how EFL teachers used IC test results to inform their teaching. The research used a bounded system, purposive and snowball sampling, and four EFL teachers. Data collection involved an online IC test and semistructured interviews. The findings indicated that EFL teachers with higher IC demonstrated increased cultural sensitivity and responsiveness in their teaching practices, leading to perceptions of inclusive and engaging learning environments for culturally diverse students. The researcher acknowledged the challenges of measuring and assessing IC as a requirement for EFL teachers and recognized the limitation of a small sample size. Future research should explore effective strategies for integrating IC assessments into EFL teacher training programs and investigate larger and more diverse samples to enhance generalizability. The study contributed to two conceptual frameworks, one based on EFL teachers' perspectives and the other aligned with the research question, problem, and purpose. It underscored the significance of incorporating culturally responsive teaching practices in EFL teacher training programs, professional development, and pedagogy to promote effective intercultural communication and foster inclusive learning environments. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]