Perhaps the most triumphant casting ever

There is no way the filmmakers could have known that Peck would reward them with the performance of a lifetime in his second movie, although clearly the directing is masterful.

And similarly every one of the other principle and even character and bit actors; Thomas Mitchell, Vincent Price, Rose Stradner, Roddy McDowall, Edmund Gwenn, Cedric Hardwicke, Peggy Anne Garner, Jane Ball, James Gleason, Anne Revere, Ruth Nelson, Benson Fong, Leonard Strong, Dennis Hoey(*), and Arthur Shields - some of them established acting greats, and some of them relatively inexperienced newcomers, like Peck himself - every one of them was excellent.

Seldom has a greater acting harmony come together. So I say the casting was triumphant, partly because of the use of excellent established actors, but more yet by taking such a huge chance with Peck, and also by picking Stradner, in one of her very few English language roles.

(*) Hoey was uncredited as the father of Peck's character.