Willingness to communicate (WTC) is the construct of a language learner's readiness to communicate with a specific person using the target language at a particular time (MacIntyre et al, 1998). This study aimed to investigate Chinese English learners' WTC in an international school in Thailand. The study used semi-structured interviews to identify the possible factors that could impact Chinese students' WTC in the international school context and how a different language environment (China vs Thailand) affected their WTC. Findings showed that the factors influencing the participants' WTC could be categorized according to cognitive, affective, motivational,sociocultural, and contextual variables. The study suggested that an L2-supportive learning environment can help increase the participants' self-confidence and self-esteem, which are very important factors affecting their WTC in English.