The purpose of this study was to better understand the nature of the contribution of the mentor teacher and the methods instructor in the development of professional knowledge of pre-service teachers (PSTs) to teach elementary science. The PSTs' conceptions of teaching science were also explored to see if there were changes in their ideas about teaching science and what influenced these changes during the methods semester of a field-based elementary teacher preparation program. Specifically, this study examined the perceptions of the PSTs regarding the nature of mentorship that they received for the teaching of elementary science. Participants were 144 PSTs from five field-based elementary methods sites, their mentor teachers, and their methods instructor from a university program in a large urban area. Of interest in this study was examining the extent to which PSTs actually observed science teaching in their mentor teachers' classrooms during the methods semester. Analysis of an end-of-semester survey revealed that more than one-third of the PSTs never observed their mentor elementary teachers teach science. On an encouraging note, 62% of PSTs who observed at least some science teaching reported that they perceived their teachers as modeling inquiry science teaching strategies. Regarding the perceived quality of mentor support for learning to teach science, more than 90% of PSTs reported that they felt supported by mentor teachers in their growth of science teaching even if the mentor teachers did not incorporate science lessons into their school day. In addition, half of the PSTs' conceptions of teaching science changed over the methods semester, with the methods course and the elementary classroom as the two most influential factors.