Through a longitudinal, qualitative study of 55 managers engaged in mobile careers across organizations, industries, and countries, and pursuing a one-year international master’s of business administration (MBA), we build a process model of the crafting of portable selves in temporary identity workspaces. Our findings reveal that contemporary careers in general, and temporary membership in an institution, fuel people’s efforts to craft portable selves: selves endowed with definitions, motives, and abilities that can be deployed across roles and organizations over time. Two pathways for crafting a portable self—one adaptive, the other exploratory—emerged from the interaction of individuals’ aims and concerns with institutional resources and demands. Each pathway involved developing a coherent understanding of the self in relation to others and to the institution that anchored participants to their current organization while preparing them for future ones. The study shows how institutions that host members temporarily can help them craft selves that afford a sense of agentic direction and enduring connection, tempering anxieties and bolstering hopes associated with mobile working lives. It also suggests that institutions serving as identity workspaces for portable selves may remain attractive and extend their cultural influence in an age of workforce mobility.