Professionalism has been a focus of educational study in recent years, with researchers trying to find out if teachers demonstrate certain qualities, mainly external, of being a professional teacher. Instead of focusing on professionalism, this paper narrows its focus to the internal aspect of teacher professional development, examining the development of Hong Kong student-teachers’ professional beliefs, about which the student-teachers hold strong opinion, and which affect their decision-making and are subject to change. This present paper is based on a pilot study involving a total of eight student-teachers. Qualitative research methods, including autobiographies and in-depth interviews, were used to conduct the research. This paper attempts to identify and describe the patterns of development of Hong Kong student-teachers’ professional beliefs, to compare the differences between various patterns and to highlight some key factors influencing professional beliefs. Implications from the study would shed light on future research on the development of student-teachers’ professional conviction.