Empirical studies have found that participation in international service increases learners' intercultural competence, language skills, appreciation of cultural differences, and tolerance for ambiguity. While previous studies suggest that international service experience is potentially transformative in nature, the present study examined international service experience and explored the factors that encourage transformation. Based on transformative learning and social psychology, the theoretical framework of the present study included three perspectives: environment-person interaction, schema adjustment, and the Johari Window. Data were obtained from 10 international service participants by observation, semistructured interviews, and written documents. Analysis of the data identified three components that enhanced transformation through environment-person interaction in cross-cultural settings: exploring the unknown world, relearning from the basic levels, and the unknown self revealed. (Contains 2 figures.)