Using a communities-of-practice framework, this qualitative study investigated what eight teachers learned about literacy teaching and learning through participation in the National Board for Professional Teaching Standards certification process. This article presents two selected teacher cases which suggest that the National Board process created a "perturbation" in the teachers' practice that helped them develop new ways of thinking and speaking about it. The level of participation in a National Board support group made a difference in the ways in which these teachers changed their conceptions of their work.