This paper investigates the effects of a sustained professional development project in South Australia in which a small group of preschool educators worked with the authors to develop their own knowledge and skills in facilitating young children's mathematical learning. Through the development of an approach to pedagogy that linked the mandated learning outcomes for preschools in South Australia to powerful mathematical ideas, the preschool educators have changed their practices in mathematics education and the ways in which they think about these practices. As well, implementation of a narrative assessment approach has provided opportunities not only for the enhancement of children's learning but also enhancement of the educators' mathematical knowledge and skills. After providing background about current research on effective pedagogy in preschools, the paper considers the impact of the professional development project on the early childhood educators, particularly in terms of their growth in knowledge, skills and confidence in early childhood mathematics. (Contains 7 tables.)