Born in Boston and raised in Dayton, Ohio, Janney received a scholarship to study at the Royal Academy of Dramatic Arts following her graduation from Kenyon College. After years of minor and uncredited film and television appearances, Janney's breakthrough came with the role of C. J. Cregg in the NBC political drama "The West Wing" (1999–2006), for which she received four Primetime Emmy Awards. In 2014, she won the Primetime Emmy Award for Outstanding Guest Actress in a Drama Series for her role as Margaret Scully on the Showtime period drama "Masters of Sex". Since 2013, she has starred as a cynical recovering addict in the CBS sitcom "Mom".