Science without Borders (SWB)/Ciência sem Fronteiras (CsF) is a Brazilian migration-for-development program that has sent post-secondary students to Canada or other developed countries around the world to study STEM subjects. The program began in 2011 and has seen thousands of students participate in coming to Canada. Despite the requirement to return to Brazil immediately after the study period in Canada has ended, some former SWB participants have decided to (im)migrate back to Canada, facing new experiences and challenges when compared to their first time in the country. In this paper, I use a transnational lens to explore the factors affecting transnational identity formation for this group of student-migrants turned (im)migrants to Canada. I argue that, by examining the factors that affect the development of transnational identities for (im)migrants, we can better understand the different routes that (im)migrants take and why. My findings indicate that the types of challenges participants faced were both an outcome and a cause of their agency and the development of their transnational identities. The decision-making strategies that participants used to respond to various challenges were also relevant to the process of negotiating these identities and developing a sense of belonging to one or more places. This research draws on findings from the analysis of personal accounts and self-perceptions obtained through semi-structured qualitative interviews with sixteen former SWB participants who have returned to Canada.