In light of increased cross-border movements of students to pursue their academic studies, university educators in many contexts are concerned about a lack of interactive engagement among students from different cultural backgrounds because of the use of L2 in international programmes. This study explores how students develop engagement in intercultural learning settings via mixed-group project work in an international curriculum provided by a Chinese university. 19 students in six mixed project groups participated in this qualitative study at three time points during one semester, with collected data including videoed project meetings after class and student presentations in class, student interviews, and student reflective essay writing. Analyses of video data identified the multifaceted nature of student engagement in intercultural learning, including collaborative, cognitive, emotional, and intercultural engagement, as well as their non-linear changing trajectories. Contrastive analysis of students' interviews and reflections between successful and less successful groups further identified factors affecting student engagement. Implications are discussed for international and intercultural curriculum design to promote student engagement in intercultural learning.