AP Style and Chicago Style: 15 Major Differences

If you’re a copy editor, you likely use AP style for some projects and Chicago for others. Problem is, keeping track of where the two styles diverge can be a challenge. Here’s a guide to help you out.

AP StylebookChicago Manual of Style
Academic Degree AbbreviationsUse periods in B.A., M.A., Ph.D. and other similar abbreviations.Do not use periods in BA, MA, PhD, and other similar abbreviations.
Co- PrefixHyphenate words that begin with the co- prefix when indicating occupation or status:
co-author, co-worker. Also hyphenate words
like co-op and co-opt for clarity. Otherwise, do not hyphenate: coexist, copay.
In general, do not hyphenate words that begin with the co- prefix: coauthor, coexist, copay, coworker. Exceptions: co-op, co-opt.
ColonCapitalize the first word after a colon if it begins a complete sentence or if it’s a proper noun.In general, lowercase the first word after a colon, even if it begins a complete sentence. Exceptions: capitalize the first word if it’s a proper noun or if the colon is introducing a question, quotation, or series of related sentences.

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