30: How do I turn on auto-fill mode by default? To turn on auto-fill mode just once for one buffer, use "M-x auto-fill-mode". To turn it on for every buffer in a certain mode, you must use the hook for that mode. For example, to turn on auto-fill mode for all text buffers, including the following in your .emacs file: (add-hook 'text-mode-hook 'turn-on-auto-fill) If you want auto-fill mode on in all major modes, do this: (setq-default auto-fill-hook 'do-auto-fill)