This paper appraises the conceptual development of mentoring in nursing and highlights the need for further research on mentoring that focuses on conceptual clarification and theoretical discovery. Despite an abundance of published articles on mentoring, a paucity of research studies on nurse-to-nurse mentoring exists. Nursing literature abounds with descriptive terminology about mentoring rather than explanatory research. Descriptive terminology does little to develop the concept of mentoring, leaving one to ponder how to implement mentoring relationships in nursing. Published research has primarily focused on two broad categories: mentor characteristics and mentoring relationship outcomes. Although numerous scholars have asserted the need to clearly conceptualize mentoring, limited research focus has contributed to an ambiguous understanding of mentoring. Research that clarifies mentoring as a concept and provides a theoretical explanation of the mentoring relationship will fill a long-standing gap in the literature.