Julius C. Jefferson, Jr., is the Section Head of the Research and Library Services Section in the Foreign Affairs, Defense, and Trade Division at Congressional Research Service of the Library of Congress. In this role, Jefferson leads research librarians who provide public policy research assistance exclusively to Members of Congress, Congressional Committees and Staffers. He also previously served as the Acting Chief of Research & Reference Services at the Library of Congress.

Jefferson served as the 2020-2021 President of the American Library Association (ALA). He has also served on a number of critical ALA committees, including the Finance and Audit Committee, the Budget Analysis and Review Committee and the Intellectual Freedom Committee, serving as the 2010-11 Chair.

In addition to his service to the American Library Association, Jefferson has held a seat on the Board of the Freedom to Read Foundation (2012-16) serving as the 2013-16 president; served as president of the District of Columbia Library Association (DCLA); and served on the board of the Black Caucus of the American Library Association (BCALA). Jefferson is currently the chair of the International Federation of Library Associations and Institutions (IFLA) North America Regional Division. 

An often called upon authority/speaker on issues of importance to library workers, Jefferson has appeared on a number of media outlets, including National Public Radio. He is co- editor of The 21st-Century Black Librarian in America: Issues and Challenges and is often sought as a speaker on library-related issues such as diversity, leadership and professional development.