This research explores the mechanisms which underlie the process of internationalisation in higher education institutions. The overall research design stands strictly on the principles of qualitative research and the logic of deductive-inductive reasoning. The University of Hong Kong (HKU) is selected as a case study and interviews are used to gather the perceptions of key institutional actors on the current changes in internationalisation activities and the mechanisms underlying such changes.In the first part of this research, a literature review and analysis on the concept of internationalisation and theory of organisational change was conducted. Based on the institutional theory, different mechanisms emerged as relevant to explain the internationalisation processes in universities.The second part of the research is the presentation of fieldwork findings which reveal that internationalisation is taking place actively and rigorously in HKU, and changes in such activities in recent years are obvious.