This two-phase study determined the landscape and intent of medical school peer mentoring programs in the U.S., U.S. Territories and Canada and, as far as can be determined, is the first of its kind. Insights from established peer mentoring programs, discovered by exploring their purpose, design, evaluations and outcomes, formed the evidence-based foundation for an emerging best practices program model. An online survey on peer mentoring administered to all allopathic and osteopathic medical schools in North America with liaisons to the accreditation agency, AAMC (92% of all schools), generated a 43% response rate. 82.9% of respondents reported they had a peer mentoring program, thus, at least one third (35.7%) of all medical schools have a peer mentoring program. The second phase was a follow-up phone interview with a subset (44.3%) of respondents from the survey. According to survey results, the purpose for initiating peer mentoring programs was to provide practical knowledge (100%) and give social support (98%). Promoting professionalism was significantly associated with survey participant's perception of effective programs. Design components significantly associated were: structured mentor-mentee meetings that followed an agenda; structured guidelines about defined roles for mentors and mentees; guidelines for mentors concerning privacy and confidentiality; mentor specialized training including interpersonal communication skill and stress management training; and assessment tools for mentors. Employed only by 15.5% of programs, mentee skills assessment was found to be perceived as significantly effective. Interviewed medical educators reinforced the survey findings and additionally contributed that when stakeholders find they are valued, it supports program success. Based on discoveries from the two phases, I proposed the Claremont Peer Mentoring Model for Medical Students, an emerging best practices model. The approach for this investigation was to generate data concerning the value of peer mentoring in medical schools. I discovered that specific aspects of purpose, design and evaluation of current peer mentoring programs significantly contribute to perceptions of effective programs giving evidence that medical student peer mentoring programs are contributing to medical education in North America. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]