This study examines the diverse roles and professional development needs of K-12 school librarians in the Greater DC area, particularly within the Mid-Atlantic Public Schools System (MAPSS, a pseudonym). The researcher used mixed methods research, to identify their needs and goals. The outcome of this study will inform the development of a mentoring program to support early career development. The research identifies school librarians' needs in their roles as leaders, instructional partners, information specialists, teachers, and program administrators. It evaluates the perceived value of mentoring programs on their professional growth. The study employed surveys and interviews to gather both quantitative and qualitative data. Surveys provided measurable insights, while interviews offered deeper context. This combined approach enabled the examination of various factors affecting school librarians, including organizational culture and professional expectations. Key findings highlighted the diverse roles of K-12 certified public school librarians and the value of mentorship on their effectiveness and professional growth. Surveys emphasized the importance of collaboration, data literacy, educational technology integration, and information literacy. School librarians also identified teaching skills and program administration as areas of interest. Mentorship was deemed crucial, with mentored librarians reporting greater success and non-mentored librarians expressing a desire for mentorship. The study's findings informed the development of a proposed mentoring program, emphasizing the necessity for tailored mentoring initiatives aligned with various competency levels and educational needs. The practical implications stress the importance of mentorship in nurturing professional growth and addressing evolving educational requirements. Future research should focus on structured mentoring programs to comprehensively support novice librarians. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]