Many voices have been heard crying for improved teaching in the classrooms of schools across America. The cry for educational reform has included the need to hold teachers accountable for student learning in their classrooms and for teachers to be knowledgeable of the content they are teaching and the methods by which they present their content. The purpose of this study was to examine the impact of the rigorous process undertaken for National Board for Professional Teaching Standard Certification on the teaching practices and professional development of three elementary physical education teachers. National Board certification was introduced to the physical education community in late Fall 2000. The three teachers in this study were among the first 289 physical education teachers to experience the rigors of this certification process. The primary investigator facilitated a study group with the three teachers and met with the candidates twice monthly to mentor them through the writing process of the four portfolio entries submitted for certification. Data were triangulated for each candidate through formal interviews, reflective writing submitted as documentation for portfolio entries, and field notes constructed following each study group meeting. Data were sorted and categorized according to emergent themes (Lincoln & Guba. 1985). A case narrative was compiled for each candidate according to the emergent themes. A cross-case analysis examined similarities and differences among the three cases. The results indicated the emergence of six themes for all three candidates, although the significance of the six themes varied by individual candidate. Documentation of student learning proved to be challenging for all three candidates, as each candidate had to articulate how knowledge constructed by the learner met learning goals. All three candidates described changes in their instructional practices in regards to student assessment as a result of their analysis of student work. As a result of reflection on instructional practices, candidates identified new goals for improved teaching strategies. These goals included: use of more indirect teaching methods to enable children to construct meaningful knowledge, the development of thematic activity in a blocked schedule of practice rather than a distributed schedule, and the inclusion of concepts to facilitate a thorough understanding of motor skills. The results indicate that the reflective process involved in National Board Certification enables master teachers to experience professional development that may lead to continued program refinements, improved teaching, and ultimately student learning.