Mentorship plays an important role in the experiences of undergraduate researchers, and students may interact with multiple potential mentors in laboratory settings. Using qualitative methods, we explored the relationships between undergraduate students engaged in research and their mentors in faculty-led laboratories, with particular attention to the roles that mentors play in the enculturation of undergraduates into science. Students rarely considered faculty as their primary mentors, rather whomever they spent the most time or worked most closely with--usually a graduate student or postdoc. There was a large disparity between women and men students identifying as scientists, and in the criteria by which they claim science identity. However, nearly all faculty members considered undergraduate researchers as scientists. This suggests that faculty members might boost the science identity of undergraduate women by simply calling them scientists.