Using a communities-of-practice framework, this 2-year qualitative study centered on five elementary teachers the year following their participation in the National Board for Professional Teaching Standards certification process. Focused on teachers' appropriation of the Board's standards and portfolio as conceptual tools related to literacy instruction, the study suggests that the National Board process does provide a learning opportunity for teachers and can positively impact teachers' practice over time. However, personal and institutional constraints influence the degree to which teachers are able to implement instruction aligned with National Board standards. (Contains 1 table.)