This study explores how engineering students develop learner agency in an intercultural PBL (problem- and project-based learning) environment, along with the factors that affect their development. Theoretically, learner agency is framed within three interrelated dimensions: intrapersonal, behavioural, and environmental. A narrative inquiry approach is adopted to investigate 11 engineering master's students' perceptions of their agency development. The findings reveal 10 elements perceived as ways to develop learner agency of engineering students, namely belief in their own self-efficacy, motivation, global engineering identity, goal-setting, planning, monitoring, reflecting, trust building, team atmosphere, and support from supervisors and institutions. These results also show that different factors affect the building of learner agency for engineering students, such as students' experiences before undertaking a master's degree, their level of advancement in the program, the culture of each study program, communication styles, and the composition of the project group.