First Lady Laura Bush had announced her daughter's engagement in August, but plans for the wedding – including whether it would take place at the White House -- have been kept strictly under wraps.
"It's going to be a small wedding," an unidentified source told People, according to the magazine's website.
Hager, 29, hails from Richmond, Virginia and is in his final year at the University of Virginia's Darden School of Business.
Jenna Bush, 26, has worked as a teacher and with the UN children's agency in Panama, and is the author of a book, Ana's Story: A Journey of Hope, based on her experiences working for UNICEF in Latin America.
She and her mother are writing a children's book about a mischievous school boy, publisher HarperCollins announced last year.
Bush's other twin daughter, Barbara, is not married.