This mixed methods study was conducted within a highly diverse K-12 public charter school setting to address a need for targeted professional development related to the development of intercultural competence for teachers in public schools, given the growing gap observed between the cultural backgrounds of K-12 public school teachers and their students. The study examined the influence of a ten-session professional development workshop training series on (a) the development of intercultural competence in teachers as measured by the Intercultural Development Inventory (IDI) and (b) teacher capacity for self-reflection on potential personal biases, awareness of others from different cultural backgrounds, managing emotions while navigating complex conversations regarding cultural and racial differences, and making meaningful and authentic connections with students and families from the different cultures which make up the school community. The Intercultural Development Continuum and Transformative Learning Theory were utilized as theoretical frameworks for this study. Participants were introduced to concepts related to intercultural competence, engaged in group discussion both in person and online, reviewed tools and strategies for classroom implementation, and completed the Intercultural Development Inventory at the beginning and conclusion of the workshop sessions. Following the series of workshop sessions, quantitative data analysis indicated growth of approximately 14% for the group of participants on the Intercultural Development Continuum, and qualitative data analysis provided evidence of participant progression through the stages of Transformative Learning Theory, resulting in new patterns of action and behavior. Discussion of findings include implications for practice and for further research.