The paper aims to clarify the relationship between individual and situational factors that relate to mentoring support. We propose that a) two individual factors, the mentors' altruism and protégés' core self-evaluations (CSE), b) one situational factor, mentors' perceived dissimilarity to their protégés, and c) the interaction of the individual and situational factors will relate to the overall mentoring support received by protégés. Results gathered from 196 mentoring dyads show that both mentors' altruism and protégés' CSE relate positively to the protégés' receipt of mentoring support, whereas mentors' perceived dissimilarity to their protégés relates negatively to the mentoring support protégés received. Furthermore, the relationship between dissimilarity and mentoring support is stronger for mentors with low altruism and for protégés with low CSE. The paper discusses factors important for fostering nurturing mentoring relationships in the workplace.