Since the mid-1990s, teacher professional community has achieved increasing influence as a strategy for facilitating productive change in schools. This study investigates the impact of principal quality and leadership on the development of teacher professional community in Hong Kong primary schools. More specifically, we examine the means by which principal quality, leadership, and organizational trust impact the strength of teacher professional community. Using survey data from 32 Hong Kong primary schools, we found that principals are crucial for the development of teacher professional community. Implications of the major finding are discussed in terms of research, policy, and practice.