Case study techniques were used to investigate perceptions of undergraduate music majors participating as teacher/mentors for elementary students in a university sponsored music composition program. Data included teacher interviews and observation of teacher training and composition mentoring sessions. Teacher perceptions were categorized as challenges and benefits for the young composers they worked with and for themselves as mentors in the program. Benefits to young composers were identified as social development, pride in accomplishment, and promotion of musical learning. Challenges to young composers were perceived as: expression of musical ideas and concern with finding "correct" ideas. Personal challenges for teachers were time commitment and encouraging students without influencing their ideas. Teachers cited benefits of participation as: teaching experience, understanding compositional process, improved composer identity, and appreciation for composer intent. Teachers envisioned possibilities for composition instruction in their future teaching situations. Implications for improving composition training for preservice teachers are discussed.