Even though a large number of studies have been conducted on the topic of international students from China, they have mostly focused on the higher education level and little attention has been paid to those young students at the secondary level. The impacts of international sojourning experiences on those at a younger age may be different from those who are older because they are at a more malleable age. Using global citizenship as the framework and guided by grounded theory, this paper examines the impacts of education overseas on Chinese students studying in American high schools, and the mechanisms through which the impacts take place. The data were collected from interviews with 15 Chinese students studying at American high schools and 7 teacher participants who work closely with them. Findings reveal that international sojourning could potentially serve as an effective pathway to global citizenship because it may help international students develop relevant knowledge and understanding, skills, as well as values and attitudes. The paper argues that the process of growing into a global citizen may be viewed as an advanced level of student development and the mechanisms through which this kind of ideal transformation takes place which were identified in this study include: Having non-vanity motives, developing self-authorship, getting exposed to different perspectives, and experiencing disadvantages and deprivation.