James Stewart (Jefferson Smith)
Jean Arthur (Clarissa Saunders)
Claude Rains (Sen. Joseph Paine)
Edward Arnold (Jim Taylor)
Thomas Mitchell (Diz Moore)
Guy Kibbee (Gov. Hubert Hopper)
Beulah Bondi (Ma Smith)
Eugene Pallette (Chick McGann)
Harry Carey (President of the Senate)
Larry Simms (One of the Hopper Boys)
Jack Richardson (Senator Manchester)
Frank Puglia (Handwriting expert)
Alex Novinsky (Foreign diplomat)
Russell Simpson (Allen)
Walter Soderling (Sen. Pickett)
Wyndham Standing (Senator Ashman)
Paul Stanton (Flood)
Craig Stevens
Carl Stockdale (Sen. Burdette)
William Newell (Reporter)
Gene Morgan (Reporter)
Charles Moore (Porters)
Arthur Loft (Chief clerk)
Hank Mann (Photographer)
Margaret Mann (Nun)
Philo McCullough (Senator Albert)
Matt McHugh (Reporter)
George McKay (Reporter)
Lafe [Lafayette] McKee (Civil War veteran)
James McNamara (Reporter)
Robert Middlemass (Speaker)
James Millican (Senate reporter)
Dub Taylor (Reporter)
Ferris Taylor (Sen. Carlisle)
Jack Cooper (Photographer)
Dulce Daye (Reporter)
June Gittelson (Woman)
Ed Randolph (Senate reporter)
Victor Travers (Senator Grainger)
Florence Wix (Committeewoman)
Count Stefanelli (Foreign diplomat)
Harry A. Bailey (Senator Hammett)
Allan Cavan (Ragner)
Robert Walker (Senator Holland)
Hal Cooke (Reporter)
John Russell (Hopper Boy)
Arthur Thalasso (Doorman)
Fred "Snowflake" Toones (Porter)
Laura Treadwell (Mrs. Taylor)
Lloyd Whitlock (Schultz)
Dave Willock (Senate guard)
William Arnold (Reporter)
George Cooper (Waiter)
Lloyd Ingraham (Committeeman)
Dick Jones (Page boy)
Frank O'Connor (Senator Alfred)
Delmar Watson (Jimmie Hopper)
Erville Alderson (Handwriting expert)
Edmund Cobb (Sen. Gower)
Dorothy Comingore (Girl)
Nick Copeland (Senate reporter)
Anne Cornwall (Senate reporter)
Gino Corrado (Barber)
Maurice Costello (Diggs)
Beatrice Curtis (Paine's secretary)
Vernon Dent (Senate reporter)
Clyde Dilson (Reporter)
Rev. Neal Dodd (Senate chaplain)
Harlan Briggs
Dora Clement (Mrs. McGann)
George Chandler (Reporter)
Stanley Andrews (Sen. Hodges)
Sam Ash (Senator Lancaster)
Frank Austin (Inventor)
Adrian Booth
Wade Boteler (Family man)
Al Bridge (Sen. Dwight)
Frederick Burton (Sen. Dearhorn)
Ken Carpenter (Announcer)
Jack Carson (Sweeney)
Maurice Cass (Handwriting expert)
Eddy Chandler (Reporter)
Ann Doran (Paine's Secretary)
Helen Jerome Eddy (Paine's secretary)
Vera Lewis (Mrs. Edwards)
Harry Hayden (Speaker)
Louis Jean Heydt (Soapbox speaker)
Fred Hoose (Senator)
Olaf Hytten (Butler)
John Ince (Senator Fernwick)
Frank Jaquet (Sen. Byron)
H.V. Kaltenborn (Broadcaster)
Eddie Kane (Reporter)
Robert Emmett Keane (Editor)
Donald Kerr (Reporter)
Milt Kibbee (Senate reporter)
Joseph King (Summers)
Evelyn Knapp (Reporter)
Wright Kramer (Senator Carlton)
Mary Gordon