We present an exploratory study of how undergraduates' involvement in research influences postgraduates (i.e., graduate and postdoctoral researchers) and faculty. We used a qualitative approach to examine the relationships among undergraduates, postgraduates, and the faculty head in a research group. In this group, undergraduates viewed postgraduates as more approachable than the faculty head both literally and figuratively. Mentorship by postgraduates presented unique challenges for undergraduates, including unrealistic expectations and varying abilities to mentor. The postgraduates and faculty head concurred that undergraduates contributed to the group's success and served as a source of frustration. Postgraduates appreciated the opportunity to observe multiple approaches to mentoring as they saw the faculty head and other postgraduates interact with undergraduates. The faculty head viewed undergraduate research as important for propagating the research community and for gaining insights into undergraduates and their postgraduate mentors. These results highlight how the involvement of undergraduates and postgraduates in research can limit and enhance the research experiences of members of the undergraduate-postgraduate-faculty triad. A number of tensions emerge that we hypothesize are intrinsic to undergraduate research experiences at research universities. Future studies can focus on determining the generalizability of these findings to other groups and disciplines. (Contains 2 tables.)