Faculty-student interaction is critical for quality undergraduate education. Faculty mentorship provides concrete benefits for students, faculty members, and institutions. However, little is known about the effect of institutional context on mentorship. Using data from interviews of 98 faculty at five different California State University institutions, we examined faculty motivations and institutional supports and barriers to mentoring as it occurs outside of formalized programs. We argue that this type of mentoring is distinct from advising and teaching and constitutes extra-role behavior. Further, institutional norms and the culture of the academic profession often hinder mentorship. Implications for policy and practice are discussed.