In recent years, the migration of people from Myanmar into Thailand has increased tremendously. Since 2005, when the Thai government officially allowed migrant children to enroll in Thai government schools, there has been a steady increase in the number of migrant students. In such a context, it is imperative that teachers develop multicultural competence, or the knowledge, skills, and attitudes required to work with culturally diverse students. However, teachers in Thailand reported that they have not been trained in the knowledge and skills to teach in multicultural classrooms. The study has two main objectives. Firstly, it attempts to design a multicultural education training program that incorporates modules that will lead to building and strengthening teachers’ multicultural competence. Secondly, it implements the training program, and measures the level of multicultural competence of teachers who received the training by comparing them to those who do not receive the training. Results revealed that teachers appraised the module about cultures of migrant students and the module about the rules and regulations in enrolling and graduating migrant students as the most useful. Results from an independent-samples t-test showed that the overall multicultural competence level of teachers who participated in the program was significantly different from those who did not participate; teachers who took part in the training demonstrated a higher level of multicultural competence compared to those who did not participate.