In Hong Kong, preschool education has been viewed either as preparation for primary education or as custodial care to suit working mothers. These ambiguous images of preschool teachers and teaching are definitely a roadblock to professionalization. This paper critically analyzes the professionalization of preschool education in the local context. Arguing that quality of practice is the cornerstone for improving the status of preschools and their teachers, it examines the complexity of professional knowledge and practice from two aspects: building knowledge and using knowledge. The former concerns child development theory as the knowledge base for practice and the latter addresses the factors affecting transformation of knowledge to pedagogy in the classroom context. Finally, it suggests that action research may provide a better grounding for professionalization.