A point of clarification -- what David refers to as "style" is, in writing,
more properly called "voice."  "Style" refers to those important issues of
standardization.  For that, yes, Chicago is widely used.  I have also found
Garner's Oxford Dictionary of American Usage and Style to be invaluable. 
(As well as our old friend Fowler, of course.)

However, museums must often address specialized topics with highly
specialized vocabularies, not covered in these general references.  In my
experience, many museums do not have a label style sheet to address these
issues.  Those that do tend to develop their own, organically and
idiosyncratically.  (I have found it useful to compile a list of the issues
as they come up and the decisions that are made.)

For graphic issues such as type face, font size, contrast, etc., the
Smithsonian has a good guide book.

But none of this helps you actually write an engaging, coherent sentence. 
For that, I must concur with those who have recommended Serrell's "Exhibit
Labels: An Interpretive Approach."  It is the best work out there on label
*writing* -- length, voice, layers, reading levels, etc.

Eugene Dillenburg
Exhibit Developer
The Science Museum of Minnesota

=========================================================
Important Subscriber Information:

The Museum-L FAQ file is located at http://www.finalchapter.com/museum-l-faq/ . You may obtain detailed information about the listserv commands by sending a one line e-mail message to [log in to unmask] . The body of the message should read "help" (without the quotes).

If you decide to leave Museum-L, please send a one line e-mail message to [log in to unmask] . The body of the message should read "Signoff Museum-L" (without the quotes).