Little research directly targets supervisors of fieldwork students in public libraries. This article identifies their feelings and behaviors using Lev Vygotsky’s zone of proximal development theory as a background for design and discussion of results. Fieldwork activities, supervisor assessments, and self-perceived roles are discussed. The study began with an online survey (77 respondents solicited by email) and continued with follow-up questions (25 respondents). Results indicate fieldwork supervisors see themselves as mentors, serving as the ‘more capable peer’ according to Vygotsky, and they guide students from supervised to unsupervised work. Suggestions for further research are given.