This paper describes data from focus groups conducted with elementary teacher mentors at two Professional Development School (PDS) sites. The focus group sessions emphasized four themes: teachers' decisions to get involved in a PDS, teachers' perceived barriers to PDS success, how teachers benefit from PDSs, and recommendations for improvement. Teachers decided to become involved in the PDS for such reasons as: needing help, being mandated by the principal, and believing that children would benefit from the effort. Participants listed many benefits for students, teachers, preservice teachers, parents, and principals, including: lower teacher-student ratios, a positive approach to working out problems, and sharing the needs of students. Respondents named several barriers that inhibited collaboration and inquiry, including: lack of information about the extensiveness of the projects, time factors, and student teachers' skill levels. Some of their recommendations included: remind new mentor teachers of goals for the student teachers, have student teachers participate in lunchroom and playground duties, and describe boundaries to student teachers. Teachers stated that the PDS had met their expectations and they looked forward to participating again. Student teachers also made positive comments about their PDS experiences. (Contains 21 references.) (SM)