She attended Kenyon College in Gambier, Ohio, where she majored in theatre. During her freshman year, Janney met actors Paul Newman and Joanne Woodward at a play for the inaugural event of the college's newly built Bolton Theater, which Newman was directing. The couple encouraged her to continue acting and offered her guidance during the early days in her career. She went on to train at the Neighborhood Playhouse School of the Theatre in New York and then received a scholarship to study at the Royal Academy of Dramatic Art in the summer of 1984.