The purpose of this exploratory mixed-methods action research study was to expose six students studying Oral Communications 1 (OC1) at Japan's Technical University (JTU) to a sociocultural component using the textbook "Mirrors and Windows" (Huber-Kriegler, Lazar, & Strange, 2003) over an eight-week period with the assistance of project-based learning (PBL). Both quantitative and qualitative data were collected using: (a) the IDI, (b) field notes, (c) reflective student journals, (d) worksheets from in-class tasks, and (d) a focus group. This dissertation used Mertler's (2014) step-by-step process of action research to collect, document, and to analyze data concerning the students' changes in intercultural competence. The Intercultural Development Inventory (IDI) was used as the primary quantitative source of data in addition to categorized quantified anecdotes from the qualitative sources using meta-inferences. A case study was constructed using the qualitative sources (the field notes, worksheets, and focus group) through narrative analysis to further elaborate on the results from the IDI. Both quantitative and qualitative interpretations showed successful improvement in three participants' intercultural competence--from polarization defense to minimization--after the completion of the curriculum adjustment. Furthermore, analysis of the case study illustrated why some students were able to transcend polarization defense while others failed. Through the action research process improvements to the sociocultural component, methodology, and theoretical framework for future studies are discussed. [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.]