This article characterizes meanings that science teaching students give to their training course and to the experiences that contribute to their professional development. In-depth interviews and personal meaning maps were used with teaching students of different training levels of a biology and science teaching program. Our results show that the set of meanings on the training course are determined by the trainees-teachers interactions, the integration of knowledge, values, feelings and emotions, and the development of professional identity. Moreover, for the participants of this study, the most important experiences they faced appear during the first year of their training, and the least gratifying are associated with mentor teachers.