Teachers are encouraged to be active professionals in their work. Consequently, the development of professional agency in student teachers is an important dimension in teacher education. This paper reports on a study where the practice of six early childhood student teachers enrolled in a Bachelor of Education (Teaching) course was analysed, using Giddens' concept of agency, and each was found to have operated with agency. However, when additional criteria pertaining to early childhood professional practice were applied by means of a triadic viewpoint only three of the student teachers were deemed to have operated with "professional" agency. Factors that were perceived to have contributed to or detracted from the student teachers' capacity to operate with professional agency were identified. Arising from these factors, this paper argues for in-depth student teacher preparation for the practicum in order to develop professional agency.