Changing the font in Aquamacs?

Question

I've recently had a need to do a bit of lisp editing and I found the nifty Ready Lisp package for OS X, which is great, except Aquamacs automatically uses a proportional font (which is idiotic, IMHO) and I want to change it to a monospace font. However, I'm not really much of an EMACS user, and the preferences menu in Aquamacs is less than clear on where and how one might make such a change.

Answer 1

From the EmacsWiki Aquamacs FAQ:

To change the font used to display the current frame, go to the font panel. You can do this with the keystroke Apple-t, or via the menu: Options → Show/Hide → Font Panel. Once there, select the font you want.

To make the current frame’s font the default, go to Options → Frame Appearance Styles. Select “use current style for foo mode”, where foo is the mode of the current frame (e.g., foo=text for text mode), to use the current style (including the font, but also any other changes you’ve made to the frame’s style) for all files of this type. Select “use current style as default” to use the current style for all files for whose major mode no special style has been defined.

There are also recommendations for monospaced fonts - Monaco or "Vera Sans Mono".

Answer 2

Fast forward a decade, for recent Aquamacs like ver 3.3 please see the nice solution for setting a fixed-width by default at https://emacs.stackexchange.com/questions/45135/change-permanently-font-size-in-aquamacs

Here's the relevant bit for those who are REALLY impatient but please go upvote that answer, user @nega deserves credit here

(when window-system
  (setq initial-frame-alist nil)   ;; Undo Aquamacs forced defaults
  (setq default-frame-alist nil)   ;; Undo Aquamacs forced defaults
  (aquamacs-autoface-mode -1)      ;; Use one face (font) everywhere
  (set-frame-font "Menlo-12")      ;; Set the default font to Menlo size 12
  ;;(set-default-font "Menlo-12")  ;; This would do the same.
)