Bob Perry, Elspeth Harley and Sue DockettThis paper is a report of a sustained professional development project in South Australia in which a small group of preschool teachers worked with the authors to develop their own skills in facilitating young children?s mathematical learning through investigative approaches and their own assessment of this learning through the use of learning stories. After providing some background information about the project, this paper considers the impact of the project on the early childhood educators themselves and their growth in knowledge, skills, and confidence in early childhood mathematics.