This study uses a phenomenological approach to exploring the lived mobilities of transnational STEM graduates navigating the study-to-work transition in the United States as part of the Optional Practical Training F-1 visa extension. Given that OPT entails a "visa extension," those on the program remain designated as F1 students whose presence in the US is designated as "temporary" and "non-immigrant" for the purpose of "full time" study or "training" (Grimm, 2019; USCIS, 2018). Yet at the same time, these students must complete their degree before they begin OPT. Such a designation places persons on OPT in between study and work, home and host country, as they take the next steps toward their career. Thus, OPT blurs the boundaries between higher education, employers, and the state. The narratives shared within this dissertation depict how the guidelines and timelines of OPT--as well as OPT's positionality within the broader U.S. immigration regime--shape the temporal, spatial, and relational dimensions of international students' post-graduation mobility experiences. In other words, I examine how the necessities of the study to work transition and of considering one's future in the face of immigration requirements and realities influence how graduates experience their time being in the United States and their relationships during these transitions. I contend these accounts encourage us to think not only how the OPT policy enables international graduates to remain and pursue work in the United States, but also to how the policy constrains these possibilities, challenging graduates to navigate experiences of urgency, ambiguity, unsettledness, and impermanence. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]