What was the first comic with both Superman and Batman?

[Pandelemin]

Was it an issue of one of their titles, or something else, like World's Finest? I'm curious!

[Kid Kyoto]

justice Society? maybe? that was around 1941 or 42.

[Mon-el]

All Star Comics #7

This thread will help you out. (http://forums.comicbookresources.com/showthread.php?t=205289)