Q. OK, so the one-space-between-sentences debate has been beaten to death. However, are there any instances where putting two spaces between two things is appropriate?
A. Nope! Not in Chicago style. One of the steps our editors include in their final manuscript cleanup before typesetting is to run a macro that changes every instance of two spaces to one. Where extra space is needed (such as for indentations), it is created with tabs or paragraph settings, not by entering multiple spaces. Sometimes a writer uses spaces to create complex content (such as poetry or “word pictures”) that the editor wants to preserve. In that case, the editor must send special instructions to prevent the typesetters from messing everything up with their own macros.