Professional development (PD) can enhance educators' knowledge and beliefs, but research has yet to determine the nature and extent of such change. This study examined the patterns and predictors of change in knowledge and beliefs for early childhood educators participating in state-implemented PD. Results from a longitudinal piecewise growth model indicated that educators improved their knowledge and beliefs to varying extents during the school year when PD was provided. Change then plateaued with educators neither improving nor regressing during the subsequent school year. Openness to change and self-efficacy significantly predicted knowledge and beliefs, respectively. Research and practice implications are provided. [This article was published in "Teaching and Teacher Education," v52 p47-55 Nov 2015.]