Despite widespread evidence of the concept of mentoring in nursing, it has been largely undefined, borrowed from other disciplines, viewed as static, and/or confused with related terms. Building on the work of Yoder and using a literature-based method developed by Rodgers, an evolutionary concept analysis is presented to provide an understanding of the meaning of mentoring in nursing, its current status, and the conceptual clarity necessary for additional systematic and rigorous inquiry. A random sample of 82 research abstracts and journal articles, representing 26 per cent of the total population of literature, was used to extract six essential attributes of the concept: a teaching-learning process, a reciprocal role, a career development relationship, a knowledge or competence differential between participants, a duration of several years, and a resonating phenomenon. These attributes form the theoretical definition of mentoring in nursing. Antecedents, consequences, related concepts, and empirical referents are presented. A model case, encompassing all of the critical attributes, depicts the Investigators' mentoring experience. Major changes in mentoring are viewed within the context of nursing as a learned profession, a legitimate academic enterprise, and a clinical science. Implications for further development are posed to further mentoring as a process for the socialization of nurse scholars and scientists and the proliferation of a body of professional knowledge.