[4] Jefferson is additionally a section head of the Congressional Research Service at the Library of Congress,[5] and served as the president of the Freedom to Read Foundation from 2013 to 2016.

He originally dreamed of being a drummer for Earth, Wind & Fire, but credits his inspiration of working in libraries to Arturo Alfonso Schomburg, and claimed to become a bibliophile.

[12] Jefferson is Chair of the International Federation of Library Associations (IFLA) North America Regional Division.

[13] In 2023 Jefferson received the Joseph W. Lippincott Award for his lifelong mentoring of librarians and library workers; commitment to equity, diversity and inclusion (EDI); and for leadership in the profession in a variety of roles, most notably during the pandemic.

[14] In 2021 Jefferson was honored with the Distinguished Terrapin Award by the University of Maryland iSchool for excelling in his field of expertise and providing value to the communities in which he serves.