This paper reports on a study of developmental thinking and qualities of reflection exhibited by two groups of music student teachers at two universities using different cooperating teacher training programs. The study examined the weekly journals of 19 music student teachers at Institution A (with trained cooperating teachers) and 26 students at Institution B (with untrained cooperating teachers). Students from Institution A used open-ended narratives to report on their weekly activities and to reflect on their teaching, while Institution B students reported their activities on more standard forms and then wrote a paper at the end of the semester in which they reflected on their student teaching experiences. Analysis suggested that the differing weekly reporting instruments rather than differences in the training of cooperating teachers contributed most to the differences in developmental growth between the two groups. The forms used at Institution A were open-ended and apparently more conducive to a wide-ranging narrative about many aspects of the student teaching experience whereas the forms used at Institution B asked for responses to specific areas and appeared to elicit briefer and less reflective responses. However, the final papers written by the Institution B students exhibited significant amounts of reflection. The findings support the value of providing students with an opportunity to "think on paper" about the activities, experiences, failures and successes of teaching. (Contains seven references.) (ND)