Globalization has exerted pressure on educational leaders to prepare students for an increasingly complex world. Institutions of higher education in the United States are striving to transform students into global citizens, and translating these imperatives into specialized curricula. However, no common definition for "global citizen" exists, nor do definitive standards concerning components of global citizenship programs. This study addressed such gaps in post-secondary global citizenship education, as well as the absence of consideration of the teaching and learning processes as part of curriculum and programming, and the dearth of student voices in existing research and writing on the subject. Using critical case study methodology, I examined students' perceptions of their global citizen identity development within the context of Lehigh University's Global Citizenship Program (GCP). My research employed qualitative techniques and a survey providing statistical data, and stemmed from two questions: How do young adults in a university-based global citizenship education program perceive their global citizen identity and the progress they have made toward becoming global citizens? What do these young adults believe influenced the development of this identity? I focused on four cohorts of students enrolled in the GCP between fall 2004 and spring 2009. Each student, charged with developing a personal definition of global citizen and designing a course of study to arrive at this identity, represented an individual case. Mezirow and Associates' (2000) theory of transformative learning in adults and Daloz's (2000) extension of this, transformative learning for social responsibility, provided the theoretical lens through which I examined my findings. Students moved from an initial conception of global citizenship as the acquisition of knowledge and competencies in the short term to the recognition that being a global citizen involved an ongoing process of learning and growth. The most important elements in students' development of their global citizen identity were constructive engagement with those who were different; opportunities to pursue social activism; engagement in discussion with peers, faculty, and others; and membership in a mentoring community. All students indicated they had made developmental progress based on their definitions of global citizen. Thirty-nine respondents (61%) believed they must do more toward developing their global citizen identity, primarily by incorporating activism. This study is significant because it informs current debates regarding the role of higher education in preparing globally ready students and in how best to facilitate self-reflection and transformative learning in young adults. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]