Mentoring relationships involve a more experienced individual who provides support for the career and personal development of a less experienced coworker. The focus of mentoring research has evolved over the years. Early on, investigators were interested in learning about the outcomes of the mentoring relationship for the protégé, who is the primary beneficiary of the relationship. Risks for the protégé were not acknowledged in the initial research on mentoring relationships. There were questions about how individuals identify appropriate mentoring partners and about the course of the relationship. Attention then turned to the motivations and potential benefits to the mentor, the other party in the relationship. However, scholars recognized that while there were positive outcomes from serving as a mentor, there were also costs associated with the role. Given that so much empirical focus was on the benefits of voluntary developmental relationships, scholars became interested in more formal, organizationally controlled approaches to encouraging mentoring relationships. However, mentoring relationships are not uniformly positive and beneficial to the parties so engaged. Just as would be the case in any relationship, there is a “dark side” to mentoring relationships that has emerged as the focus of empirical attention. Finally, the influence of diversity of the mentoring participants has been explored. That exploration has largely focused on gender issues, with limited attention devoted toward ethnicity. With the advent of greater diversity in the workforce in the United States and elsewhere, diversity represents an area ripe for investigation. Overall, despite the wealth of research on mentoring relationships, there are questions that remain under-researched or unexplored in each of the areas of research.