Public accounting firms can build integrity within their organizations through early detection of fraud. One way to reduce and detect fraud is to encourage whistleblowing as a prosocial behavior. We explore the impact of mentoring on intention to report fraud. A survey with 120 responses from the US public accountants suggests that quality mentoring relationships, a common feature in the profession, and caring ethical climate positively relate to internal reporting of fraud. Two intermediate variables, trust and affective commitment, mediate these effects. Mentor-relationship quality also increases perceptions of caring ethical climate. The study contributes to two bodies of research by (1) finding extended benefits from mentoring, beyond those typically discussed in academic literature; and (2) identifying a previously unexplored firm intervention capable of positively influencing prosocial behavior and combating fraud.