Current recommendations for achieving high quality professional development for teachers include the creation of a professional learning community wherein each member of the educational community--student, teacher, parent, community, principal, and staff--is both teacher and learner. Key to the success of this approach, however, is the role of the peer mentor or coach. This study was designed to determine what it takes to be a successful professional development coach by gathering data based on the perspectives and experiences of 31 peer coaches. Results suggest that, while content expertise is important, coaches must possess strong interpersonal skills in order to build trusting relationships with teachers. These relationships, then, enable coaches to use their content expertise to facilitate changes in teachers' practice. Suggestions for selecting and training peer coaches are included. (Contains 25 references.) (Author/SM)