Published in JAMA, the following systematic review analyzes the evidence about the prevalence of mentorship and its relationship to career development. Less than 50% of medical students and in some fields less than 20% of faculty members had a mentor. Women perceived that they had more difficulty finding mentors than their colleagues who are men. Mentorship was reported to have an important influence on personal development, career guidance, career choice, and research productivity, including publication and grant success. To enhance the development of mentorship within academic institutions and to prevent further erosion of these vital relationships, it is important to understand the effect of mentorship on the mentees (and mentors), the variables associated with mentoring success, and the impact of mentoring interventions on career satisfaction and productivity.