Commentary: Personal Transformations and the Possibilities of Incremental Progress in Mathematics Teacher Professional Development

In this commentary, I challenge the field to take seriously the idea of incremental professional development (PD) for teachers of mathematics. I begin by briefly describing the history of PD in the United States since the publication of NCTM's Curriculum and Evaluation Standards, what we have learned about effective PD through research, and then pose set of dilemmas we face in having a wide impact on the teaching of mathematics in the United States. Through reflecting on my story of incremental and transformative change as a high school mathematics teacher and 28 years as a mathematics teacher educator and scholar, I argue that the concept of incremental PD is worthy of exploration.