Although mentoring others and career plateaus are both common experiences for seasoned employees, they are rarely examined together. In this study, we considered mentoring others as an antecedent of career plateaus and emotional exhaustion and turnover intentions as outcomes of career plateaus for mentors. We also examined the moderating role of mentors' proactive personality. Results of hierarchical regression analyses based on 188 mentoring dyads indicated that career-focused mentoring alleviated both hierarchical and job content plateauing perceptions. Mentors' proactive personality moderated the relationship between career-focused mentoring and hierarchical plateauing such that the negative relationship is stronger for low proactive personality mentors. Hierarchical plateaus were positively related to mentors' emotional exhaustion and turnover intentions whereas job content plateaus only positively related to turnover intentions. Proactive personality moderated the relationship between job content plateaus and mentors' work-related attitudes such that the positive relationships were stronger for more proactive mentors. The implications and future research suggestions are discussed.