Jason Robards

Character: Narrator (voice)

Red Barber

Character: Self - Radio Announcer

Erik Barnouw

Character: Self - Historian

Ken Bilby

Character: Self - Biographer of David Sarnoff

Norman Corwin

Character: Self - Writer

Susan Douglas

Character: Self - Historian

Frank Günther

Character: Self - Engineer

Jeanne Hammond

Character: Self - Niece of Edwin H. Armstrong

Loren Jones

Character: Self - Engineer

Garrison Keillor

Character: Self - Writer

Helen Kelley

Character: Self - Radio Broadcaster

Robert Morris

Character: Self - Engineer

Dana Raymond

Character: Self - Friend of Edwin H. Armstrong

Gertrude Tyne

Character: Self - Engineer

Fred Allen

Character: Self - Predicts Demise of Radio (archive footage)

Gene Autry

Character: Self - Sings (archive sound)

John Barrymore

Character: Hamlet (archive sound)

Winston Churchill

Character: Self - Finest Hour Speech (archive sound)

Charles J. Correll

Character: Self - Prepares for Amos 'n' Andy Broadcast (archive footage)

Lee De Forest

Character: Self - Objects to Quality of Radio Programming (archive footage)

Ralph Edwards

Character: Self - Host of 'This Is Your Life' (archive footage)

Dwight D. Eisenhower

Character: Self - Announces Landing in Normandy (archive footage)

Eugenia Farrar

Character: Self (with Lee De Forest) (archive footage)

Freeman F. Gosden

Character: Self - Prepares for Amos 'n' Andy Broadcast (archive footage)

Guglielmo Marconi

Character: Self - Visits Sarnoff at RCA (archive footage)

Marie Mosquini

Character: Self - with Lee De Forest (archive footage)

Nelson Rockefeller

Character: Self - Eulogizes Sarnoff (archive footage)

Franklin D. Roosevelt

Character: Self - Makes Broadcast About Banking Reform (archive footage)

David Sarnoff

Character: Self - with Marconi at RCA (archive footage)

Frank Sinatra

Character: Self - Serenades Sarnoff (archive footage)

Arturo Toscanini

Character: Self - Conducts NBC Symphony (archive footage)

Harry S. Truman

Character: Self - Announces Bombing of Hiroshima (archive sound)

Bob Warren

Character: Self - This is Your Life Announcer (archive footage)

Orson Welles

Character: Self - Professor in War of the Worlds Broadcast (archive sound)