Q. I’m wondering about the ampersand versus and in journal titles. There are two examples where past editions of Chicago used and for a journal whose title online has an ampersand (Past and Present; Trends in Ecology and Evolution). Is it fair to extrapolate from these examples that Chicago would recommend replacing the ampersand in citations of journals?
A. If the ampersand is on the journal’s cover (or cover image) and elsewhere at the journal publisher’s website (e.g., an About page or the like), then you can safely retain the ampersand. If there’s any doubt about the journal title, however (perhaps a particular journal is inconsistent in its usage over the years), use and. See also CMOS 13.90 (for some permissible changes to titles of works; changing an ampersand to and is among the permissible changes).