Evidence suggests that student teaching is one of the most influential components of a teacher education program, and the cooperating teacher exerts the greatest influence on a student teacher. Therefore, it is vital to understand how the role of experienced teachers is affected by the implementation of a professional development school (PDS) as these individuals assume greater responsibility in the education of prospective teachers and in their own professional development. This paper synthesizes extant research related to the roles cooperating teachers assume under a PDS model and offers possibilities for the continued development of these roles. It first provides background on the PDS movement and describes traditional roles cooperating teachers have assumed. It then outlines organizational and personal prerequisites germane to ensuring that experienced teachers in PDSs become more intimately involved in teacher education and professional development. Positive effects as well as challenges of teachers' altered roles are described with implications for the success of future PDS endeavors. (Contains 1 note.)