In 1973, Kavner auditioned for a role as one of Rhoda Morgenstern's sisters in "The Mary Tyler Moore Show". David Davis, producer of the show, had convinced her to audition for the part, but decided to cast another actress instead. A year later, Rhoda Morgenstern became the leading character in a spin-off called "Rhoda". Kavner was cast in her first professional acting role as Brenda Morgenstern, sister of the eponymous character. "Rhoda" ran on CBS from September 9, 1974, to December 1978. She received four Primetime Emmy Award nominations for Outstanding Continuing Performance by a Supporting Actress in a Comedy Series for playing Brenda, winning in 1978. She also received four Golden Globe Award nominations. In 1975, she received Daytime Emmy Award nomination for her starring role in the daytime special "The Girl Who Couldn't Lose".