Objectives:The research objectives were to (1) describe the current and future roles of hospital librarians and the challenges they face and (2) find evidence supporting the hypothesis that librarians are essential to hospitals in achieving the organizations' mission-critical goals.Method:The authors used results from a previous research study that identified the five organizational mission-critical goals important to hospital administrators and then searched the literature and solicited examples from hospital librarians to describe the librarian's role in helping hospitals achieve these goals.Results:The literature supports the hypothesis that hospital librarians play important roles in the success of the hospital. Librarians support quality clinical care, efficient and effective hospital operations, continuing education for staff, research and innovation, and patient, family, and community health information needs.Conclusion:Hospital librarians fulfill many mission-critical roles in today's hospital, providing the right information at the right time in a variety of ways to enhance hospital and medical staff effectiveness, optimize patient care, improve patient outcomes, and increase patient and family satisfaction with the hospital and its services. Because hospital librarians and their services provide an excellent return on investment for the hospital and help the hospital keep its competitive edge, hospital staff should have access to the services of a professional librarian.