The present study was about developing a diversity education programme for adults to enhance competencies in diversity and inclusion. The programme covered various diversity topics and employed participatory learning methods such as intergroup dialogue, discussion, and theatre in education (TIE). Furthermore, the programme was structured in a modular format to allow flexible adaptation to different needs of learners and organizations. We tested six modules in two training programmes with separate participant groups, assessing their awareness, emotions, and behaviours before and after training. Findings highlight the effectiveness of interactive, participation-oriented learning in diversity-related education. In South Korea, diversity-related education, including multicultural programmes, often relies on lecture-based methods and specific content areas. However, our research suggests that a broader range of topics and interactive approaches significantly enhance diversity training outcomes, particularly in fostering behavioural change. Limitations and future directions for research, in expanding interactive approaches and evaluating their long-term impact, are discussed.