Monk will play Alexandra Kirby, a glitzy radio show host who will become Nora's (Sally Field) rival when she is asked to host an Ask Mom-style radio program.
Monk won a Tony Award for Redwood Curtain and an Emmy Award for a guest appearance on "NYPD Blue." Additional stage credits include Curtains; Chicago; Reckless; Thou Shalt Not; Steel Pier; Company; Picnic; Nick and Nora; Prelude to a Kiss; Pump Boys and Dinettes (which she co-authored); The Seagull; The Time of the Cuckoo (Obie Award); Assassins and Oil City Symphony (also co-author; Drama Desk Award). She has also appeared on "Grey's Anatomy" and "Desperate Housewives."
"Brothers and Sisters" airs Sundays at 10 PM ET on ABC. The season premiere is scheduled for Sept. 26.